GBT Global Blood Therapeutics Inc

You are cordially invited to attend a special meeting (including any adjournments or postponements thereof, which we refer to as the “Special Meeting”) of stockholders of Global Blood Therapeutics, Inc., a Delaware corporation (which we refer to as “GBT”, the “Company”, “we”, “us” and “our”) to be held virtually via live webcast on September 30, 2022, beginning at 8:00 a.m. Pacific Time (unless the Special Meeting is adjourned or postponed). GBT stockholders will be able to virtually attend and vote at the Special Meeting by visiting www.virtualshareholdermeeting.com/GBT2022SM, which we refer to as the “Special Meeting website”. For purposes of attendance at the Special Meeting, all references in the enclosed proxy statement to “present” shall mean virtually present at the Special Meeting.

At the Special Meeting, you will be asked to consider and vote on (a) a proposal to adopt the Agreement and Plan of Merger, dated as of August 7, 2022 (as it may be amended from time to time, which we refer to as the “Merger Agreement”), by and among Pfizer Inc., a Delaware corporation (which we refer to as “Parent” or “Pfizer”), Ribeye Acquisition Corp., a Delaware corporation and a wholly owned subsidiary of Parent (which we refer to as “Merger Sub”), and GBT (which we refer to as the “Merger Agreement Proposal”), (b) a proposal to approve, on an advisory (nonbinding) basis, the compensation that may be paid or become payable to GBT’s named executive officers that is based on or otherwise related to the Merger Agreement and the transactions contemplated by the Merger Agreement (which we refer to as the “Compensation Proposal”) and (c) a proposal to adjourn the Special Meeting, if necessary or appropriate, to solicit additional proxies if there are insufficient votes to adopt the Merger Agreement at the time of the Special Meeting (which we refer to as the “Adjournment Proposal”). Pursuant to the terms of the Merger Agreement, subject to the terms and conditions set forth therein, Merger Sub will merge with and into GBT (which we refer to as the “Merger”), with GBT continuing as the surviving corporation in the Merger and as a wholly owned subsidiary of Parent.

The Merger Agreement provides that, subject to certain exceptions, each share of common stock, par value $0.001 per share, of GBT (which we refer to as “GBT common stock”) issued and outstanding immediately prior to the effective time of the Merger (which we refer to as the “Effective Time”) will at the Effective Time automatically be converted into the right to receive $68.50 in cash, without interest (which we refer to as the “Merger Consideration”) and subject to any required withholding of tax.

If the Merger is completed, you will be entitled to receive the Merger Consideration, less any applicable withholding taxes, for each share of GBT common stock that you own immediately prior to the Effective Time (unless you have properly and validly exercised and do not withdraw your appraisal rights under Section 262 of the General Corporation Law of the State of Delaware).

The Board of Directors of GBT, after considering the factors more fully described in the enclosed proxy statement, has unanimously: (a) determined that the Merger Agreement and the transactions contemplated thereby are advisable and fair to, and in the best interests of, GBT and its stockholders; (b) approved the Merger Agreement and the transactions contemplated thereby, including the execution, delivery and performance of the Merger Agreement; (c) resolved to recommend that GBT stockholders adopt the Merger Agreement; and (d) directed that the adoption of the Merger Agreement be submitted for consideration by GBT stockholders at the Special Meeting. The Board of Directors unanimously recommends that you vote: (1) “FOR” the Merger Agreement Proposal; (2) “FOR” the Compensation Proposal; and (3) “FOR” the Adjournment Proposal.

The enclosed proxy statement provides detailed information about the Special Meeting, the Merger Agreement and the Merger. A copy of the Merger Agreement is attached as Annex A to the proxy statement.

The proxy statement also describes the actions and determinations of the Board of Directors in connection with its evaluation of the Merger Agreement and the Merger. You should carefully read and consider the entire enclosed proxy statement and its annexes, including the Merger Agreement, as they contain important information about, among other things, the Merger and how it affects you.

Whether or not you plan to attend the virtual Special Meeting, please sign, date and return, as promptly as possible, the enclosed proxy card in the accompanying prepaid reply envelope or grant your proxy electronically over the Internet or by telephone (in accordance with the instructions detailed in the section of this proxy statement entitled “The Special Meeting—Voting at the Special Meeting”). If you attend the Special Meeting and vote thereat, your vote will revoke any proxy that you have previously submitted.

If you hold your shares in “street name”, you should instruct your bank, broker or other nominee how to vote your shares in accordance with the voting instruction form that you will receive from your bank, broker or other nominee. Your bank, broker or other nominee cannot vote on any of the proposals, including the Merger Agreement Proposal, without your instructions.

Your vote is very important, regardless of the number of shares that you own. We cannot complete the Merger unless the Merger Agreement Proposal is approved by the affirmative vote of the holders of at least a majority of the outstanding shares of GBT common stock entitled to vote thereon at the Special Meeting. If you have any questions or need assistance voting your shares, please contact our proxy solicitor:

On behalf of the Board of Directors, I thank you for your support and appreciate your consideration of these matters.

Neither the Securities and Exchange Commission nor any state securities regulatory agency has approved or disapproved the Merger, passed upon the merits or fairness of the Merger or passed upon the adequacy or accuracy of the disclosure in this document. Any representation to the contrary is a criminal offense.

The accompanying proxy statement is dated August 29, 2022, and, together with the enclosed form of proxy card, is first being mailed to GBT stockholders on or about August 29, 2022.

Whether or not you plan to attend the virtual Special Meeting, please sign, date and return, as promptly as possible, the enclosed proxy card in the accompanying prepaid reply envelope or grant your proxy electronically over the Internet or by telephone (in accordance with the instructions detailed in the section of this proxy statement entitled “The Special Meeting—Voting at the Special Meeting”). If you attend the Special Meeting and vote thereat, your vote will revoke any proxy that you have previously submitted. If you hold your shares in “street name”, you should instruct your bank, broker or other nominee how to vote your shares in accordance with the voting instruction form that you will receive from your bank, broker or other nominee. Your bank, broker or other nominee cannot vote on any of the proposals, including the Merger Agreement Proposal, without your instructions. If you sign, date and mail your proxy card without indicating how you wish to vote, your proxy will be counted as a vote “FOR” the Merger Agreement Proposal, “FOR” the Compensation Proposal and “FOR” the Adjournment Proposal.

WHETHER OR NOT YOU PLAN TO ATTEND THE SPECIAL MEETING, WE ENCOURAGE YOU TO SUBMIT YOUR PROXY AS PROMPTLY AS POSSIBLE: (1) BY TELEPHONE; (2) OVER THE INTERNET; OR (3) BY SIGNING AND DATING THE ENCLOSED PROXY CARD AND RETURNING IT IN THE POSTAGE-PAID ENVELOPE PROVIDED. You may revoke your proxy or change your vote before the Special Meeting in the manner described in the enclosed proxy statement.

If you fail to (1) return your proxy card, (2) grant your proxy electronically over the Internet or by telephone or (3) vote at the Special Meeting, your shares will not be counted for purposes of determining whether a quorum is present at the Special Meeting and, if a quorum is present, will have the same effect as a vote “AGAINST” the Merger Agreement Proposal but, assuming a quorum is present, will have no effect on the Compensation Proposal or the Adjournment Proposal.

You should carefully read and consider the entire accompanying proxy statement and its annexes, including the Merger Agreement, along with all of the documents incorporated by reference into the accompanying proxy statement, as they contain important information about, among other things, the Merger and how it affects you. If you have any questions concerning the Merger Agreement, the Merger, the Special Meeting or the accompanying proxy statement, would like additional copies of the accompanying proxy statement or need help voting your shares of GBT common stock, please contact our proxy solicitor:

The following questions and answers address some commonly asked questions regarding the Merger, the Merger Agreement and the Special Meeting. These questions and answers may not address all questions that are important to you. You should carefully read and consider the more detailed information contained elsewhere in this proxy statement and the annexes to this proxy statement, including the Merger Agreement, along with all of the documents we refer to in this proxy statement, as they contain important information about, among other things, the Merger and how it affects you. You may obtain the information incorporated by reference in this proxy statement without charge by following the instructions in the section of this proxy statement entitled “Where You Can Find More Information”.

The information contained in this proxy statement regarding the proposed merger, the expected timetable for completing the proposed merger, future financial and operating results and benefits of the proposed merger, future opportunities for the combined entity, general business outlook and any other statements may include “forward-looking statements”. All statements other than statements of historical fact are statements that could be deemed forward-looking statements, including all statements regarding the intent, belief or current expectation of the companies and members of their senior management team. Readers can generally identify forward-looking statements by the use of forward-looking terminology such as “outlook”, “potential”, “continue”, “may”, “seek”, “approximately”, “predict”, “believe”, “expect”, “plan”, “intend”, “poised”, “estimate” or “anticipate” and similar expressions or the negative versions of these words or comparable words, as well as future or conditional verbs such as “will”, “should”, “would”, “likely” and “could”. Forward-looking statements include, without limitation, statements regarding the transactions and related matters; prospective performance and opportunities; post-closing operations and the outlook for the companies’ businesses; filings and approvals relating to the transactions; the expected timing of the transactions; the ability to complete the transactions considering the various closing conditions; and any assumptions underlying any of the foregoing. Investors are cautioned that any such forward-looking statements are not guarantees of future performance and involve risks and uncertainties and are cautioned not to place undue reliance on these forward-looking statements. We can give no assurance that the plans, intentions, expectations or strategies will be attained or achieved, and, furthermore, actual results may differ materially from those described in the forward-looking statements and will be affected by a variety of risks and factors that are beyond our control, including, without limitation, uncertainties as to the timing of the transactions; the risk that the transactions may not be completed in a timely manner or at all; risks and uncertainties related to receiving the approval of GBT’s stockholders; the possibility that competing offers or acquisition proposals for GBT will be made; the possibility that any or all of the various conditions to the consummation of the transactions may not be satisfied or waived, including the failure to receive any required regulatory approvals from any applicable governmental entities (or any conditions, limitations or restrictions placed on such approvals); the risks that drug-related adverse events may be observed during commercialization or clinical development; the risk that data and results may not meet regulatory requirements or otherwise be sufficient for further development, regulatory review or approval; risks related to clinical trials and other studies (including the anticipated timing of clinical data, the funding therefor, anticipated patient enrollment, trial outcomes, timing or associated costs); the occurrence of any event, change or other circumstance that could give rise to the termination of the definitive agreement for the transactions, including in circumstances which would require GBT to pay a termination fee; the effect of the announcement or pendency of the transactions on GBT’s ability to retain and hire key personnel, its ability to maintain relationships with its third-party payors, customers, distributors, suppliers and others with whom it does business or its operating results and business generally; risks related to diverting management’s attention from GBT’s ongoing business operations; the risk that stockholder litigation in connection with the transactions may result in significant costs of defense, indemnification and liability; difficulties or unanticipated expenses in connection with integrating the companies; and other factors discussed in the “Risk Factors” and the “Management’s Discussion and Analysis of Financial Condition and Results of Operations” sections of GBT’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021, filed with the Securities and Exchange Commission SEC on February 23, 2022, and in our most recent Quarterly Report on Form 10-Q filed with the SEC, as well as discussions of potential risks, uncertainties and other important factors in our subsequent Current Reports on Form 8-K and other filings with the SEC. In addition to the risks described above, other unknown or unpredictable factors also could affect GBT’s results. As a result of these factors, we cannot assure you that the forward-looking statements in this communication will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all.

The forward-looking statements in this communication represent our views as of the date of this communication. We anticipate that subsequent events and developments may cause our views to change. However, while we may elect to update these forward-looking statements at some point in the future, we undertake no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law. You should, therefore, not rely on these forward-looking statements as representing our views as of any date subsequent to the date of this communication. You should read this communication and the documents that we reference in this communication completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of our forward-looking statements by these cautionary statements.

The enclosed proxy is solicited on behalf of the Board for use at the Special Meeting.

The Special Meeting will held virtually via live webcast on September 30, 2022, beginning at 8:00 a.m. Pacific Time (unless the Special Meeting is adjourned or postponed). GBT stockholders will be able to virtually attend and vote at the Special Meeting by visiting www.virtualshareholdermeeting.com/GBT2022SM. Online check-in will start approximately 15 minutes before the Special Meeting is scheduled to begin.

At the Special Meeting, we will ask GBT stockholders to vote on proposals to: (a) adopt the Merger Agreement Proposal; (b) approve, on an advisory (nonbinding) basis, the Compensation Proposal; and (c) approve the Adjournment Proposal.

Only GBT stockholders as of the Record Date are entitled to notice of the Special Meeting and to vote at the Special Meeting. A list of GBT stockholders entitled to vote at the Special Meeting will be available at our principal executive offices located at 181 Oyster Point Boulevard, South San Francisco, CA 94080, during regular business hours for a period of no less than 10 days before the Special Meeting, as well as on the Special Meeting website. If GBT’s headquarters are closed during such period for health and safety reasons related to the COVID-19 pandemic, the list of GBT stockholders will be made available for inspection upon request to our Secretary at 181 Oyster Point Boulevard, South San Francisco, CA 94080, subject to the satisfactory verification of GBT stockholder status. The list will also be available electronically during the Special Meeting on the Special Meeting website. As of the Record Date, there were 67,476,179 shares of GBT common stock outstanding and entitled to vote at the Special Meeting.

The presence, in person or represented by proxy, of the holders of a majority of the shares of GBT common stock entitled to vote on the Record Date will constitute a quorum at the Special Meeting. In the event that a quorum is not present at the Special Meeting, it is expected that the Special Meeting will be adjourned to solicit additional proxies.

Each GBT stockholder shall be entitled to one vote for each share of GBT common stock owned at the close of business on the Record Date.

The affirmative vote of the holders of a majority of the outstanding shares of GBT common stock entitled to vote thereon is required to approve the Merger Agreement Proposal. As of the Record Date, 33,738,090 votes constitute a majority of the outstanding shares of GBT common stock. Adoption of the Merger Agreement by GBT stockholders is a condition to the consummation of the Merger.

The affirmative vote of the holders of a majority of the shares of GBT common stock properly cast for the Compensation Proposal is required to approve, on an advisory (nonbinding) basis, the Compensation Proposal.

The affirmative vote of either (a) a majority of the shares of GBT common stock properly cast for and against the Adjournment Proposal, when a quorum is present, or (b) the affirmative vote of the holders of the shares of GBT common stock representing a majority of the voting power present at the Special Meeting, when a quorum is not present, is required, as applicable, for approval of the Adjournment Proposal.

If a quorum is present at the Special Meeting, for GBT stockholders who attend the Special Meeting or are represented by proxy and abstain from voting, the abstention will have the same effect as if the GBT stockholder voted “AGAINST” the Merger Agreement Proposal but, assuming a quorum is present, will have no effect on the Compensation Proposal and the Adjournment Proposal. If a quorum is not present, abstentions will have the same effect as a vote “AGAINST” the Adjournment Proposal.

Each “broker non-vote” will also count as a vote “AGAINST” the Merger Agreement Proposal but, assuming a quorum is present, will have no effect on the Compensation Proposal or the Adjournment Proposal. A

so-called “broker non-vote” results when banks, brokers and other nominees return a valid proxy voting upon a matter or matters for which the applicable rules provide discretionary authority but do not vote on a particular proposal because they do not have discretionary authority to vote on the matter and have not received specific voting instructions from the beneficial owner of such shares. GBT does not expect any broker non-votes at the Special Meeting because the rules applicable to banks, brokers and other nominees only provide brokers with discretionary authority to vote on proposals that are considered “routine”, whereas each of the proposals to be presented at the Special Meeting is considered “non-routine”. As a result, no broker will be permitted to vote your shares of GBT common stock at the Special Meeting without receiving instructions. Failure to instruct your broker on how to vote your shares will have the same effect as a vote “AGAINST” the Merger Agreement Proposal.

As of the Record Date, our directors and executive officers beneficially owned and were entitled to vote, in the aggregate, 1,585,803 shares of GBT common stock, representing approximately 2.35% of the shares of GBT common stock outstanding on the Record Date.

We currently expect that each of our directors and executive officers will vote all of their respective shares of GBT common stock (1) “FOR” the Merger Agreement Proposal, (2) “FOR” the Compensation Proposal and (3) “FOR” the Adjournment Proposal.

You can vote at the virtual Special Meeting, which will be held on September 30, 2022, at 8:00 a.m. Pacific Time at www.virtualshareholdermeeting.com/GBT2022SM (unless the Special Meeting is adjourned or postponed).

You may also authorize the persons named as proxies on the proxy card to vote your shares by returning the proxy card in advance by mail, over the Internet or by telephone. Although GBT offers four different voting methods, GBT encourages you to vote over the Internet or by phone as GBT believes they are the most cost-effective methods. We also recommend that you vote as soon as possible, even if you are planning to attend the Special Meeting, so that the vote count will not be delayed. Both the Internet and the telephone provide convenient, cost-effective and reliable alternatives to returning your proxy card by mail. If you choose to vote your shares over the Internet or by telephone, there is no need for you to submit your proxy card by mail.

Vote at www.proxyvote.com in advance of the Special Meeting. The Internet voting system is available 24 hours per day until 11:59 p.m. Eastern Time on September 29, 2022. Once you enter the Internet voting system, you can record and confirm (or change) your voting instructions.

Use the telephone number shown on your proxy card. The telephone voting system is available 24 hours per day in the United States until 11:59 p.m. Eastern Time on September 29, 2022. Once you enter the telephone voting system, a series of prompts will tell you how to record and confirm (or change) your voting instructions.

Adjournment Proposal or the Compensation Proposal on a nonbinding advisory basis, your shares of GBT common stock will be voted “FOR” each such proposal. Proxy cards that are returned without a signature will not be counted as present at the Special Meeting and cannot be voted.

If your shares are held in “street name” through a bank, broker or other nominee, you may vote through your bank, broker or other nominee by completing and returning the voting form provided by your bank, broker or other nominee or attending the Special Meeting and voting using your control number, or, if you did not obtain a control number, contacting your bank, broker or other nominee to obtain a control number so that you may vote. If such a service is provided, you may vote over the Internet or telephone through your bank, broker or other nominee by following the instructions on the voting form provided by your bank, broker or other nominee. If you do not return your bank’s, broker’s or other nominee’s voting form, do not vote via the Internet or telephone through your bank, broker or other nominee, if possible, or do not attend the Special Meeting and vote thereat, it will have the same effect as if you voted “AGAINST” the Merger Agreement Proposal but, assuming a quorum is present, will not have any effect on the Compensation Proposal or the Adjournment Proposal.

Any proxy given by a GBT stockholder may be revoked before the Special Meeting by doing any of the following:

If you hold your shares of GBT common stock in “street name”, you should contact your bank, broker or other nominee for instructions regarding how to change your vote. You may also vote at the virtual Special Meeting with your control number, or, if you did not obtain a control number, by contacting your bank, broker or other nominee to obtain a control number.

Any adjournment, postponement or other delay of the Special Meeting, including for the purpose of soliciting additional proxies, will allow GBT stockholders who have already sent in their proxies to revoke them at any time prior to their use at the Special Meeting as adjourned, postponed or delayed.

The Board has unanimously: (a) determined that the Merger Agreement and the transactions contemplated thereby are advisable and fair, to and in the best interests of, GBT and its stockholders; (b) approved the Merger Agreement and the transactions contemplated thereby, including the execution, delivery and performance of the Merger Agreement; (c) resolved to recommend that GBT stockholders adopt the Merger Agreement; and (d) directed that the adoption of the Merger Agreement be submitted for consideration by GBT stockholders at the Special Meeting.

The Board unanimously recommends that you vote: (1) “FOR” the Merger Agreement Proposal; (2) “FOR” the Compensation Proposal; and (3) “FOR” the Adjournment Proposal.

The Board is soliciting your proxy, and GBT will bear the cost of soliciting proxies. Innisfree M&A Incorporated has been retained to assist with the solicitation of proxies. GBT expects to pay Innisfree M&A

Incorporated a fee of $37,500, plus certain costs associated with additional services, as necessary, and Innisfree M&A Incorporated will be reimbursed for its reasonable out-of-pocket expenses for these and other advisory services in connection with the Special Meeting. Forms of proxies and proxy materials may also be distributed through brokers, custodians and other like parties to the beneficial owners of shares of GBT common stock, in which case these parties will be reimbursed for their reasonable out-of-pocket expenses in accordance with SEC and Nasdaq regulations. Proxies may also be solicited in person or by telephone, facsimile, electronic mail or other electronic medium by Innisfree M&A Incorporated or, without additional compensation, by GBT or GBT’s directors, officers and employees.

Assuming timely satisfaction of necessary closing conditions, including the approval by GBT stockholders of the Merger Agreement Proposal, we currently anticipate that the Merger will be consummated as early as the fourth quarter of 2022. However, the exact timing of completion of the Merger cannot be predicted because the Merger is subject to the closing conditions specified in the Merger Agreement and summarized in this proxy statement, many of which are outside of our control.

If the Merger is consummated, persons who do not wish to accept the Merger Consideration are entitled to seek appraisal of their shares of GBT common stock under Section 262 and, if all procedures described in Section 262 are strictly complied with, to receive payment in cash for the fair value of their shares of GBT common stock exclusive of any element of value arising from the accomplishment or expectation of the Merger, as determined by the Delaware Court, together with interest, if any, to be paid upon the amount determined to be the fair value. The “fair value” of your shares of GBT common stock as determined by the Delaware Court may be more or less than, or the same as, the Merger Consideration that you are otherwise entitled to receive under the Merger Agreement. These rights are known as “appraisal rights”. This proxy statement serves as a notice of such appraisal rights pursuant to Section 262.

Persons who exercise appraisal rights under Section 262 will not receive the Merger Consideration they would otherwise be entitled to receive pursuant to the Merger Agreement. They will receive an amount determined to be the “fair value” of their shares of GBT common stock following petition to, and an appraisal by, the Delaware Court. Persons considering seeking appraisal should recognize that the fair value of their shares of GBT common stock determined under Section 262 could be more than, the same as or less than the Merger Consideration they would otherwise be entitled to receive pursuant to the Merger Agreement. Strict compliance with the procedures set forth in Section 262 is required. Failure to comply strictly with all of the procedures set forth in Section 262 may result in the withdrawal, loss or waiver of appraisal rights. Consequently, and in view of the complexity of the provisions of Section 262, persons wishing to exercise appraisal rights are urged to consult their legal and financial advisors before attempting to exercise such rights.

A holder of record of shares of GBT common stock and a beneficial owner who (i) continuously holds such shares through the Effective Time, (ii) has not consented to or otherwise voted in favor of the Merger or otherwise withdrawn, lost or waived appraisal rights, (iii) strictly complies with the procedures under Section 262, (iv) does not thereafter withdraw his, her or its demand for appraisal of such shares and (v) in the case of a beneficial owner, a person who (A) reasonably identifies in his, her or its demand the holder of record of the shares for which the demand is made, (B) provides documentary evidence of such beneficial owner’s beneficial ownership and a statement that such documentary evidence is a true and correct copy of what it purports to be and (C) provides an address at which such beneficial owner consents to receive notices given by the Company and to be set forth on the Chancery List (as defined in the section of this proxy statement entitled “Proposal 1: Adoption of the Merger Agreement—Appraisal Rights”), will be entitled to receive the fair value of his, her or its shares of GBT common stock exclusive of any element of value arising from the accomplishment or expectation of the Merger, as determined by the Delaware Court, together with interest, if any, to be paid upon the amount determined to be the fair value.

A copy of Section 262 may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262. The following summary is not a complete statement of the law relating to appraisal rights and is qualified in its entirety by reference to Section 262 and

any amendments thereto after the date of this proxy statement. Any person who desires to exercise his, her or its appraisal rights should review carefully Section 262 and is urged to consult his, her or its legal advisor before electing or attempting to exercise such rights. For more information, please see the section of this proxy statement entitled “Proposal 1: Adoption of the Merger Agreement—Appraisal Rights”.

If the Merger is completed, the shares of GBT common stock will be delisted from the Nasdaq and deregistered under the Exchange Act, and shares of GBT common stock will no longer be publicly traded.

If the Merger Agreement is not adopted by GBT stockholders, or if the Merger is not completed for any other reason:

At the Effective Time, by virtue of the Merger and without any action on the part of GBT, Parent, Merger Sub or the holders of any securities of GBT or Merger Sub, each share of GBT common stock (other than Excluded GBT Shares) issued and outstanding immediately prior to the Effective Time will be converted automatically into the right to receive the Merger Consideration of $68.50 in cash, without interest and subject to any required tax withholding.

After the Merger is completed, you will have the right to receive the Merger Consideration in respect of each share of GBT common stock that you own (other than Excluded GBT Shares) immediately prior to the Effective Time (subject to any required tax withholding), but you will no longer have any rights as a GBT stockholder (except that GBT stockholders who properly and validly exercise and do not withdraw their appraisal rights will have a right to receive payment of the “fair value” of their shares as determined pursuant to an appraisal proceeding, as contemplated by the DGCL). For more information, please see the section of this proxy statement entitled “—Appraisal Rights”.

At the Effective Time, subject to all required withholding taxes, equity awards granted on or prior to the date of the Merger Agreement that remain outstanding as of immediately prior to the Effective Time will be treated as follows:

At the Effective Time, equity awards that may be granted to employees of the Company after the date of the Merger Agreement and prior to the Effective Time and that remain outstanding as of immediately prior to the Effective Time will be converted into cash awards (based on the Merger Consideration multiplied by the number of shares of GBT common stock subject to the applicable award immediately prior to the completion of the Merger) subject to the same vesting schedule applicable to the corresponding award.

For more information, please see the section of this proxy statement entitled “The Merger Agreement—Merger Consideration—Treatment of GBT Equity Awards”.

The Company’s management and the Board regularly review the Company’s performance and prospects in light of its business and developments in the biotechnology and pharmaceutical industries. These reviews have included consideration, from time to time, of potential partnerships, collaborations and other strategic transactions to enhance stockholder value, including potential sale transactions. Such reviews have been accompanied by periodic conversations between senior executives of the Company and their counterparts at other companies in such industries regarding such potential transactions and opportunities.

On May 26, 2022, a representative of Company A contacted Dr. Ted W. Love, the Company’s President and Chief Executive Officer, to schedule time to speak. The representative of Company A and Dr. Love spoke on June 2, 2022 and proposed a meeting between Dr. Love and representatives of Company A. On June 6, 2022, Dr. Love and Ms. Jung E. Choi, the Company’s Chief Business and Strategy Officer, met with representatives of Company A. During this meeting, the representatives of Company A provided a letter containing a non-binding proposal to acquire 100% of the Company’s equity for $55.00 per share of GBT common stock in cash (which we refer to as the “June 6 Company A Proposal”), which proposal represented a 111% premium to the closing price for shares of GBT common stock of $26.11 on June 3, 2022, the last trading day prior to the June 6 Company A Proposal. The offer letter stated that its submission had the support of Company A’s Chief Executive Officer and Chief Financial Officer.

On June 7, 2022, management of the Company apprised the Board of the June 6 Company A Proposal and a Board meeting was scheduled for June 8, 2022 to discuss the June 6 Company A Proposal.

On June 8, 2022, the Board, along with members of management and representatives of J.P. Morgan, a financial advisor to the Company, and Cravath, Swaine & Moore LLP (which we refer to as “Cravath”) and Goodwin Procter LLP (which we refer to as “Goodwin”), outside counsel to the Company, met virtually to discuss, among other topics, the June 6 Company A Proposal. Dr. Love described to the Board his interactions with representatives of Company A prior to and following the receipt of the June 6 Company A Proposal. Members of management briefed the Board on the Company’s ongoing assessment of its long-range plans, which would be further discussed at the September 2022 strategic retreat, and the Company’s next steps in light of its receipt of the June 6 Company A Proposal. Representatives of J.P. Morgan provided a market overview and their preliminary view of the June 6 Company A Proposal, and representatives of Cravath reviewed with the members of the Board their fiduciary duties and other legal matters. The Board determined to continue to consider the June 6 Company A Proposal, following a preliminary financial analysis to be performed prior to the next Board meeting.

On June 8, 2022, the Company selected Centerview as an additional financial advisor to the Company (we refer to J.P. Morgan and Centerview, collectively, as “the Company’s financial advisors”).

On June 14, 2022, the Board, along with members of management and representatives of Cravath and Goodwin, met virtually for a regularly scheduled meeting during which, among other topics, the June 6 Company A Proposal was discussed. At the meeting, a representative of Cravath reviewed with the members of the Board their fiduciary duties and other legal matters. The Board and representatives of the Company’s financial advisors discussed, along with members of management and representatives of Cravath and Goodwin, among other topics, the June 6 Company A Proposal and certain strategic considerations in connection with a potential sale transaction, as well as an overview of other potential acquirors of the Company. Representatives of the Company’s financial advisors presented their preliminary financial review of the June 6 Company A Proposal based on preliminary financial projections provided by management. Following discussion, the Board authorized the Company’s management, with the assistance of its financial and legal advisors, to inform Company A that the June 6 Company A Proposal was insufficient from a financial perspective. However, the Board authorized the Company’s management, with the assistance of the Company’s financial advisors, to provide Company A with limited high-level information, upon execution of the confidentiality agreement, in order to enable Company A to improve its offer price. The Board also authorized the Company’s management, with the assistance of its financial and legal advisors, to solicit interest from additional potential acquirors to gauge their interest in a potential transaction with the Company and, if a potential acquiror of the Company indicated an interest in a potential transaction with the Company, to send such potential acquiror a draft confidentiality agreement and,

once entered into, commence discussions with such potential acquiror. In order to facilitate the Board providing guidance to the Company’s management during the negotiations of the potential sale transaction, the Board adopted resolutions forming a transaction committee (which we refer to as the “Transaction Committee”), consisting of Scott Morrison, Mark Perry and Dawn Svoronos. The Board decided that, while the Transaction Committee would be comprised of three members of the Board, all Board members would be invited to, and strongly encouraged to participate in, any and all meetings of the Transaction Committee. Over the next several weeks, in addition to formal Board meetings, Dr. Love and other members of the Company’s senior management periodically briefed and received input from several Board members as to the discussions with representatives of certain of the potential acquirors.

On June 15, 2022, Dr. Love and Ms. Choi met virtually with representatives of Company A. Dr. Love informed the representatives of Company A that the Board had determined that the June 6 Company A Proposal was insufficient from a financial perspective, but that, following the execution by Company A of a confidentiality agreement, Dr. Love and a limited number of other senior management of the Company would make themselves available for a conversation to help Company A learn about the Company in order to facilitate an increase in Company A’s offer price. The representatives of Company A informed the Company that Company A would send a diligence request list that would help Company A better understand the value of the Company.

Later on June 15, 2022, at the direction of the Board, representatives of the Company’s financial advisors provided a confidentiality agreement to Company A, which was negotiated over the next several days among representatives of the Company, Company A, Cravath and Company A’s outside counsel. The confidentiality agreement between the Company and Company A was executed on June 18, 2022.

On June 16, 2022, at the direction of the Board, representatives of the Company’s financial advisors spoke telephonically with representatives of Pfizer to ask whether they would be interested in exploring a potential acquisition of the Company. The following day, representatives of Pfizer contacted representatives of the Company’s financial advisors to ask whether they could receive a management presentation. Following this conversation, at the direction of the Board, representatives of the Company’s financial advisors provided a confidentiality agreement to Pfizer, which was negotiated over the next several days among representatives of the Company, Pfizer and Cravath. The confidentiality agreement between the Company and Pfizer was executed on June 27, 2022.

On June 17, 2022, at the direction of the Board, representatives of the Company’s financial advisors spoke telephonically with representatives of Company B to ask whether they would be interested in exploring a potential acquisition of the Company. The following day, representatives of Company B contacted representatives of the Company’s financial advisors to ask whether they could receive a management presentation. Following this conversation, at the direction of the Board, representatives of the Company’s financial advisors provided a confidentiality agreement to representatives of Company B, which was negotiated over the next several days among representatives of the Company, Company B and Cravath. The confidentiality agreement between the Company and Company B was executed on June 26, 2022. All of the executed confidentiality agreements contained standstill provisions, which automatically terminated upon the execution of the Merger Agreement.

Between June 15 and June 17, 2022, management spoke telephonically with one potential acquiror, and representatives of the Company’s financial advisors, at the direction of the Board, contacted two other potential acquirors, in each case that had been reviewed with the Board at the June 14 Board Meeting, all of whom declined to pursue a potential acquisition of the Company.

Between June 24 and June 28, 2022, representatives of Pfizer, Company A and Company B separately met virtually with the Company’s management for a presentation on, among other things, clinical, regulatory and commercial information in respect of Oxbryta and the Company’s product candidates, GBT601 and inclacumab, as well as an overview of the Company’s research programs.

On June 28, 2022, Dr. Love met virtually with a representative of Company A to discuss, among other things, the mechanisms of action of the Company’s products and product candidates.

On June 29, 2022, representatives of Company A called Dr. Love and Ms. Choi to request that Company A be permitted to conduct full due diligence, including being granted access to a virtual data room. In connection with such request, Company A delivered a revised non-binding proposal to acquire 100% of the outstanding

equity of the Company for $60.00 per share of GBT common stock, which offer was subsequently delivered to the Company in writing (which we refer to as the “June 29 Company A Proposal”), which proposal represented a 101% premium to the closing price for shares of GBT common stock of $29.84 on June 28, 2022, the last trading day prior to the June 29 Company A Proposal.

On July 5, 2022, the Transaction Committee, along with other members of the Board and management as well as representatives of the Company’s financial advisors, Cravath and Goodwin, met virtually to consider and discuss, among other things, the June 29 Company A Proposal and the status of discussions with other potential acquirors. Dr. Love provided the Transaction Committee with an overview of the discussions with Company A and the outreach to other potential acquirors, including Pfizer and Company B, that had occurred since the prior Board meeting on June 14, 2022. Representatives of the Company’s financial advisors also briefed the Transaction Committee on the outreach efforts since the prior Board meeting and indicated that the other potential acquirors had declined to engage in further discussions regarding a potential acquisition of the Company. Representatives of the Company’s financial advisors presented certain preliminary financial analyses of the June 29 Company A Proposal. Following discussion, the Transaction Committee determined that the Company would permit Company A to commence further due diligence to enable it to further improve its offer price. The Transaction Committee and other participating Board members directed the Company’s financial advisors to inform Company A that the June 29 Company A Proposal was still insufficient from a financial perspective, but that the Company would grant Company A full diligence access to the Company’s virtual data room in order to enable Company A to improve its offer price. Additionally, the Transaction Committee directed the Company’s financial advisors to continue to seek offers from Pfizer and Company B as a condition to such parties conducting further due diligence.

On July 6, 2022, Dr. Love and Ms. Choi met virtually with representatives of Company A. Dr. Love informed the representatives of Company A that the June 29 Company A Proposal was insufficient from a financial perspective, but that the Company would allow Company A to conduct further due diligence, with the expectation that Company A would increase its offer price following its due diligence review. The next day, Company A was granted access to a virtual data room established by the Company.

On July 6, 2022, representatives of Pfizer spoke telephonically with representatives of the Company’s financial advisors to share a preliminary list of high-priority diligence questions in order to further assess Pfizer’s potential interest in an acquisition of the Company. The next day, Dr. Love met virtually with several representatives of Pfizer to discuss, among other things, certain of such diligence questions.

On July 11, 2022, representatives of Pfizer provided a letter to Dr. Love containing a non-binding proposal to acquire 100% of the Company’s equity for $53.00 per share of GBT common stock in cash (which we refer to as the “July 11 Pfizer Proposal”), which proposal represented a 52% premium to the closing price for shares of GBT common stock of $34.85 on July 8, 2022, the last trading day prior to the July 11 Pfizer Proposal. The offer letter stated that Pfizer’s executive leadership strongly supported the proposal and proposed three weeks of due diligence to be conducted concurrently with negotiation of a definitive merger agreement. The same day, the Company’s management provided the Board with a copy of the offer letter from Pfizer, and Pfizer was granted access to the virtual data room in order to enable Pfizer to improve its offer price.

On July 12, 2022, representatives of Company B provided a letter to representatives of the Company’s financial advisors containing a non-binding proposal to acquire 100% of the Company’s equity for $50.50 per share of GBT common stock in cash (which we refer to as the “July 12 Company B Proposal”), which proposal represented a 50% premium to the closing price for shares of GBT common stock of $33.71 on July 11, 2022, the last trading day prior to the July 12 Company B Proposal. The offer letter proposed six to eight weeks of due diligence upon access to the Company’s management and the virtual data room, but, unlike Pfizer and Company A, did not indicate engagement by Company B of financial or legal advisors.

On July 13, 2022, after consultation with management of the Company, representatives of the Company’s financial advisors informed representatives of Company B that the July 12 Company B Proposal was insufficient both from a financial perspective and regarding the time to completion of diligence and that Company B would need to submit a revised offer with improved terms in order for the Company to grant Company B access to the virtual data room.

During the following weeks, Pfizer and Company A conducted their respective due diligence investigations of the Company. Representatives of the Company continued to meet virtually with representatives of Pfizer and Company A to discuss certain diligence items.

On July 18, 2022, representatives of Cravath sent a draft merger agreement to representatives of Company A’s outside counsel and to representatives of Wachtell, Lipton, Rosen & Katz, Pfizer’s legal counsel (which we refer to as “Wachtell Lipton”). The initial draft included, among other things, a proposed termination fee, which would be payable by the Company upon the occurrence of certain events, including the Company’s termination of the merger agreement to accept a superior proposal (which we refer to as a “company termination fee”), of 1.50% of transaction equity value.

On July 20, 2022, representatives of the Company’s financial advisors spoke telephonically with representatives of Pfizer to discuss, among other things, Pfizer’s desire to execute a definitive agreement by early August and the status of Pfizer’s due diligence process. During the conversation, the representative of Pfizer informed representatives of the Company’s financial advisors that Pfizer would send a revised offer in the coming days.

On July 22, 2022, representatives of Company B provided a letter to representatives of the Company’s financial advisors containing a revised non-binding proposal to acquire 100% of the Company’s equity for $58.00 per share of GBT common stock in cash (which we refer to as the “July 22 Company B Proposal”), which proposal represented a 67% premium to the closing price for shares of GBT common stock of $34.82 on July 21, 2022, the last trading day prior to the July 22 Company B Proposal. The revised offer letter proposed three weeks of due diligence upon access to the Company’s management and the virtual data room, and, consistent with its prior offer letter, did not indicate engagement by Company B of financial or legal advisors.

Over the next two days, Company B was granted access to the virtual data room in order to enable Company B to improve its offer price and representatives of Cravath sent a draft merger agreement to representatives of Company B. The terms of such draft merger agreement were identical to the terms of the draft merger agreements previously sent to representatives of Company A’s outside counsel and to representatives of Wachtell Lipton. During the following weeks, Company B conducted its due diligence investigation of the Company, although no external advisors were involved in any of the interactions. Representatives of the Company continued to meet virtually with representatives of Company B to discuss certain diligence items, however, its level of engagement was not comparable to that of Pfizer or Company A.

On July 26, 2022, representatives of Pfizer provided a letter to Dr. Love containing a revised non-binding proposal to acquire 100% of the Company’s equity for $60.00 in cash (which we refer to as the “July 26 Pfizer Proposal”), which proposal represented a 79% premium to the closing price for shares of GBT common stock of $33.52 on July 25, 2022, the last trading day prior to the July 26 Pfizer Proposal. The revised letter provided that Pfizer’s due diligence review was substantially complete, and noted that Pfizer was prepared to move expeditiously to sign a definitive merger agreement and announce the transaction within a week.

Shortly after the submission of the letter, representatives of Wachtell Lipton sent a revised draft merger agreement to representatives of Cravath. The draft included, among other things, a proposed company termination fee of 4.00% of transaction equity value.

On July 27, 2022, the Transaction Committee, along with each other member of the Board, members of management and representatives of the Company’s financial advisors, Cravath and Goodwin, met virtually to discuss, among other topics, the progress of the proposed transaction to date, including the revised offer and revised draft merger agreement from Pfizer and the status of the bids from Company A and Company B. Management of the Company and representatives of the Company’s financial advisors reviewed with the Transaction Committee the Company’s interactions with Pfizer, Company A and Company B since the prior Transaction Committee meeting on July 5, 2022. The Transaction Committee then discussed with the Company’s management and representatives of the Company’s financial advisors and Cravath the potential for the Company to obtain increased offers from each of the potential acquirors, relative timelines and relative certainty of execution and closing with each of the potential acquirors, taking into account each potential acquiror’s progress in the diligence and negotiation processes to date and timeline to execution of a definitive agreement as well as regulatory considerations.

Also on July 27, 2022, at the direction of the Board, representatives of the Company’s financial advisors informed representatives of Company A’s financial advisor that the Company was engaged in discussions with other potential acquirors.

On July 28, 2022, representatives of Company A’s outside counsel sent a revised draft merger agreement to representatives of Cravath. The draft included, among other things, a proposed company termination fee of 4.00% of transaction equity value.

On July 30, 2022, representatives of Cravath sent revised draft merger agreements to representatives of Company A’s outside counsel and to representatives of Wachtell Lipton. The drafts sent to both parties contained substantially similar terms, and each draft included, among other things, a proposed company termination fee of 2.00% of transaction equity value.

On July 31, 2022, after consultation with management of the Company, representatives of the Company’s financial advisors sent a letter to representatives of each of Pfizer, Company A and Company B instructing each party to submit a revised draft of the merger agreement to representatives of Cravath by noon, Eastern Time, on August 2, 2022, following which representatives of Cravath would provide feedback to such party. The letter further instructed each party to submit a final proposal, including a best and final offer price per share of GBT common stock and a revised draft of the merger agreement in a form that such potential acquiror would be willing to execute, by noon, Eastern Time, on August 5, 2022.

On August 2, 2022, representatives of Wachtell Lipton sent a revised draft merger agreement to representatives of Cravath. The draft included, among other things, a proposed company termination fee of 3.75% of transaction equity value and a proposed reverse termination fee, which would be payable by Pfizer if certain specified antitrust-related closing conditions were not met (which we refer to as a “reverse termination fee”), of 3.75% of transaction equity value. Later that day, representatives of Wachtell Lipton also discussed with representatives of Cravath the proposed terms, including commitments around regulatory approval and transaction structure. Also on August 2, 2022, representatives of Company A’s outside counsel sent a revised draft merger agreement to representatives of Cravath. The draft included, among other things, a proposed company termination fee of 3.00% of transaction equity value. Representatives of Company B did not submit a revised draft of the merger agreement to representatives of Cravath on August 2, 2022.

On August 3, 2022, Bloomberg News published an article online after market hours indicating that the Company was attracting takeover interest from unidentified large pharmaceutical companies. On August 3, 2022, the last trading day that closed prior to the publication of the Bloomberg News article, the closing price for shares of GBT common stock was $33.93.

On August 3, 2022, the Board, along with members of management and representatives of the Company’s financial advisors, Cravath and Goodwin, met virtually to discuss, among other topics, updated projections refined by the Company’s management reflecting certain updates since June 14, 2022, as well as the status and terms of the draft merger agreements. At the meeting, members of the Company’s management presented updated projections to the Board (as described below in the section of this proxy statement entitled “— Certain Financial Forecasts”). Following discussion, the Board authorized such projections for use by the Board in evaluating the potential transaction with Pfizer and by the Company’s financial advisors in their financial analyses in connection with the potential delivery of their respective fairness opinions. Representatives of Cravath then provided an overview of relationships each of Cravath and the Company’s financial advisors has with the potential acquirors. Representatives of Cravath next reviewed the Board’s fiduciary duties in connection with its consideration of the proposed transactions and the key legal terms of the draft merger agreements proposed by each of Pfizer and Company A. Representatives of Cravath reviewed with the Board the potential regulatory review process and timeline for a transaction with each of the potential acquirors. Representatives of Cravath and members of the Board then discussed how certain terms of the merger agreement, including certain regulatory provisions and the closing conditions, affect the likelihood of closing of a potential transaction. Representatives of the Company’s financial advisors then discussed the status of negotiations with representatives of Pfizer, Company A and Company B. In addition, disclosure regarding relationships with the Company, Pfizer, Company A and Company B of the Company’s financial advisors was reviewed with the Board and the Board approved the formal engagement terms for each of J.P. Morgan and Centerview as the Company’s financial advisors in connection with its review of a potential transaction.

On August 4, 2022, representatives of Cravath sent revised draft merger agreements to representatives of Company A’s outside counsel and to representatives of Wachtell Lipton. Each draft included, among other things, a proposed company termination fee of 2.75% of transaction equity value.

Also on August 4, 2022, representatives of Cravath met virtually with representatives of Wachtell Lipton and separately with representatives of Company A’s outside counsel to discuss certain outstanding contractual terms in the revised draft merger agreement, including regulatory commitments.

In the morning of August 5, 2022, representatives of Company A met virtually with Dr. Love and Ms. Choi to deliver a revised proposal, which was subsequently delivered to the Company in writing, to acquire 100% of the outstanding equity of the Company for $61.50 per share of GBT common stock in cash (which we refer to as the “August 5 Company A Proposal”), which proposal represented a 81% premium to the closing price for shares of GBT common stock of $33.93 on August 3, 2022, the last trading day that closed prior to public market speculation regarding a potential sale of the Company. The offer letter stated that Company A had completed due diligence and secured all approvals (including approval from its board of directors) necessary to execute the merger agreement. The offer letter indicated that the August 5 Company A Proposal was not subject to any financing requirements and that Company A was prepared to execute a definitive merger agreement on or before August 7, 2022. The offer letter requested that, if the Company elected to move forward with the August 5 Company A Proposal, the Company enter into a customary exclusivity agreement providing for exclusive negotiations until 4:30 p.m. Eastern Time on August 8, 2022. Following Dr. Love’s discussion with representatives of Company A, representatives of Company A submitted a revised draft merger agreement to representatives of the Company’s financial advisors, which draft included, among other things, a proposed company termination fee of 2.75% of transaction equity value.

Later that morning, Dr. Albert Bourla, Chief Executive Officer of Pfizer, called Dr. Love to discuss Pfizer’s commitment to SCD and to the community and indicated that Pfizer would shortly be delivering a revised proposal to the Company. In the proposal which was subsequently delivered by representatives of Pfizer to the Company in writing, Pfizer offered to acquire 100% of the outstanding equity of the Company for $67.50 per share of GBT common stock in cash (which we refer to as the “August 5 Pfizer Proposal”), which proposal represented a 99% premium to the closing price for shares of GBT common stock of $33.93 on August 3, 2022, the last trading day that closed prior to public market speculation regarding a potential sale of the Company. The offer letter stated that Pfizer had completed due diligence and secured all approvals (including approval from its board of directors) necessary to execute the merger agreement. The offer letter indicated that the August 5 Pfizer Proposal was not subject to any financing requirements and that Pfizer was prepared to execute a definitive merger agreement immediately. Subsequently, representatives of Wachtell Lipton submitted a draft of the merger agreement to representatives of Cravath, which draft included, among other things, the Company Termination Fee of $217 million (3.75% of transaction equity value) and the Reverse Termination Fee of $326 million (5.625% of transaction equity value). Company B did not submit a final offer or a draft merger agreement on August 5, 2022.

Later that morning, The Wall Street Journal published an article online indicating that Pfizer was in advanced negotiations to acquire the Company for about $5 billion and that the Company was also negotiating with other potential acquirors.

Later that same morning, in advance of the scheduled Board meeting at noon, Pacific Time, management and the Company’s financial advisors provided feedback to representatives of both Pfizer and Company A. Dr. Love contacted representatives of Company A and expressed that the August 5 Company A Proposal was insufficient from a financial perspective. Representatives of Company A subsequently indicated to Dr. Love that Company A would be willing to acquire 100% of the outstanding equity of the Company for $65.00 per share of GBT common stock in cash (which we refer to as the “Revised August 5 Company A Proposal”), which proposal represented a 92% premium to the closing price for shares of GBT common stock of $33.93 on August 3, 2022, the last trading day that closed prior to public market speculation regarding a potential sale of the Company. Following that subsequent discussion, representatives of the Company’s financial advisors contacted representatives of Pfizer to inform them that the Company had received a competing proposal from another party that was not that far apart in terms of value, and that Pfizer should also consider improving the terms of its draft merger agreement.

At noon, Pacific Time, on August 5, 2022, the Board, along with members of management and representatives of the Company’s financial advisors, Cravath and Goodwin, met virtually to discuss, among other topics, the August 5 Pfizer Proposal and the Revised August 5 Company A Proposal. First, Dr. Love provided the Board with an update on his conversations with representatives of Pfizer and Company A earlier that day, and representatives of the Company’s financial advisors updated the Board on their conversation with representatives of Pfizer. Next, representatives of Cravath reviewed the merger agreements submitted by Pfizer and Company A with their respective proposals. Representatives of Cravath compared the terms of the draft merger agreements submitted by Pfizer and Company A, including the closing conditions and certain regulatory matters. The Board and representatives of Cravath discussed the August 5 Pfizer Proposal and the Revised August 5 Company A Proposal, including that the August 5 Pfizer Proposal included a higher price per share of GBT common stock than the Revised August 5 Company A Proposal, while the merger agreement submitted by Company A was generally more favorable to the Company than the merger agreement submitted by Pfizer with respect to regulatory matters and the closing conditions. Representatives of Cravath then reviewed with the Board certain employee retention, compensation and benefits-related matters in the draft merger agreements submitted by Pfizer and Company A, including that the Revised August 5 Company A Proposal contemplated that all Company PSUs would be cashed out at the maximum level, while the August 5 Pfizer Proposal contemplated that Company PSUs based on patient share and total stockholder return would be cashed out at the greater of target and actual performance (as of the closing of the proposed transaction) and Company PSUs based on the price of GBT common stock would be canceled upon consummation of the proposed transaction. Further, the Board was advised that Company B had not engaged in any interactions with the Company’s management or advisors regarding price or contract terms since the last update to the Board. Following such discussion, the Board directed the Company’s management, with the assistance of its financial and legal advisors, to seek a revised offer from each of Pfizer and Company A.

After the noon Board meeting, Dr. Love contacted the Chief Executive Officer of Company A to seek an increase in Company A’s offer price. The Chief Executive Officer of Company A indicated that the $65.00 price per share of GBT common stock contained in the Revised August 5 Company A Proposal was likely the highest price that Company A was willing to pay to acquire the Company. In addition, at the direction of the Board, representatives of the Company’s financial advisors separately contacted representatives of Pfizer and Company A to discuss each of their proposals. During these discussions, representatives of Company A indicated to representatives of the Company’s financial advisors that they were uncertain of their ability to increase their offer above the $65.00 price per share of GBT common stock contained in the Revised August 5 Company A Proposal. Separately, representatives of Pfizer indicated to representatives of the Company’s financial advisors that they were reiterating the $67.50 price per share of GBT common stock in the August 5 Pfizer Proposal. Representatives of Cravath also contacted representatives of Wachtell Lipton in order to discuss certain terms of the draft merger agreement that impacted closing certainty, including the closing conditions.

At 4:00 p.m., Pacific Time, the Board, along with members of management and representatives of the Company’s financial advisors, Cravath and Goodwin, met virtually to discuss, among other topics, the outreach to representatives of Pfizer and Company A since the Board meeting earlier that day. Dr. Love described to the Board his discussion with the Chief Executive Officer of Company A. Additionally, representatives of the Company’s financial advisors described to the Board their separate discussions with representatives of Pfizer and Company A. Representatives of Cravath updated the Board on their discussions with representatives of Wachtell Lipton since the prior meeting. The Board directed representatives of the Company’s financial advisors to solicit “best and final” offers from each of Pfizer and Company A.

After the Board meeting, as directed by the Board, representatives of the Company’s financial advisors contacted representatives of Pfizer and representatives of Company A in order to solicit “best and final” offers. Representatives of Company A confirmed that the Revised August 5 Company A Proposal represented Company A’s “best and final” offer. Representatives of Cravath also contacted representatives of Wachtell Lipton to seek improved merger agreement terms, including with respect to the closing conditions.

At 8:00 p.m., Pacific Time, the Board, along with members of management and representatives of the Company’s financial advisors, Cravath and Goodwin, met virtually to discuss, among other topics, the outreach to representatives of Pfizer and Company A since the prior Board meeting. Representatives of the Company’s financial advisors reviewed with the Board their discussions with representatives of Pfizer and Company A since the Board meeting earlier that day. Representatives of Cravath reviewed with the Board the key terms of the

merger agreement submitted by Pfizer, including certain changes to the closing conditions that were favorable to the Company to which Pfizer had agreed. The meeting was then temporarily adjourned in order for representatives of Cravath to contact representatives of Wachtell Lipton to seek further clarification regarding Pfizer’s latest proposal on the terms of the merger agreement for the Board to consider.

During the adjournment, and subsequent to discussions between representatives of Cravath and representatives of Wachtell Lipton, at the direction of the Board, representatives of the Company’s financial advisors contacted representatives of Pfizer to solicit its “best and final” offer price, based upon the contract terms Pfizer would be willing to execute in a potential definitive merger agreement. Subsequent to this conversation, representatives of Pfizer indicated to representatives of the Company’s financial advisors that, provided the Company was willing to sign a definitive merger agreement substantially on the terms Pfizer had last presented, Pfizer would increase its offer to $68.50 per share of GBT common stock in cash (which we refer to as the “Revised August 5 Pfizer Proposal”), which represented a 102% premium to the closing price for shares of GBT common stock of $33.93 on August 3, 2022, the last trading day that closed prior to public market speculation regarding a potential sale of the Company. Additionally, representatives of Pfizer indicated that Pfizer was prepared to execute the definitive merger agreement by August 6, 2022.

Following those discussions, the Board meeting was reconvened. Representatives of Cravath reviewed with the Board the terms of the merger agreement proposed by representatives of Wachtell Lipton, including with respect to the closing conditions. Representatives of the Company’s financial advisors then provided an update to the Board on the Revised August 5 Pfizer Proposal. The Board then discussed the financial and contractual terms of the Revised August 5 Company A Proposal and the Revised August 5 Pfizer Proposal. Following such discussion, the Board directed the Company’s management, with the assistance of its legal advisors, to finalize the definitive merger agreement with Pfizer at a price per share of GBT common stock of $68.50 and on the contractual terms included in the Revised August 5 Pfizer Proposal (as updated based on conversations between representatives of Cravath and Wachtell Lipton on August 5th) and authorized the Company’s management to discuss certain employee retention, compensation and benefits-related matters with Pfizer.

After the Board meetings on August 5^th and through August 7, 2022, representatives of the Company, Pfizer, Cravath and Wachtell Lipton discussed and exchanged comments to the draft merger agreement. At the conclusion of these discussions, the parties had agreed on the final form of merger agreement. On August 6, 2022, Dr. Love had conversations with representatives of Pfizer regarding certain employee retention, compensation and benefits-related matters; these conversations did not result in revisions to the Revised August 5 Pfizer Proposal.

On August 7, 2022, the Board, along with members of management and representatives of the Company’s financial advisors, Cravath and Goodwin, met virtually to review the proposed transaction with Pfizer. Dr. Love described to the Board his discussions with representatives of Pfizer since the last Board meeting. Representatives of J.P. Morgan reviewed its financial analysis of the Merger Consideration of $68.50 per share of GBT common stock, and rendered to the Board an oral opinion, which was subsequently confirmed by delivery of a written opinion dated August 7, 2022, that, as of such date and based upon and subject to the assumptions made, procedures followed, matters considered and qualifications and limitations on the review undertaken by J.P. Morgan in preparing its opinion, the Merger Consideration of $68.50 per share of GBT common stock to be paid to GBT stockholders (other than as specified in such opinion) pursuant to the Merger Agreement was fair, from a financial point of view, to such holders. Representatives of Centerview reviewed its financial analysis of the Merger Consideration of $68.50 per share of GBT common stock, and rendered to the Board an oral opinion, which was subsequently confirmed by delivery of a written opinion dated August 7, 2022, that, as of such date and based upon and subject to the various assumptions made, procedures followed, matters considered and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion, the Merger Consideration of $68.50 per share of GBT common stock to be paid to GBT stockholders (other than Excluded Shares (as defined therein)) pursuant to the Merger Agreement was fair, from a financial point of view, to such holders. For a detailed discussion of J.P. Morgan’s opinion and Centerview’s opinion, please see the sections of this proxy statement below entitled “—Opinion of J.P. Morgan” and “—Opinion of Centerview”, respectively. The written opinions delivered by J.P. Morgan and Centerview are attached to this Proxy Statement as Annex B and Annex C, respectively. Representatives of Cravath reviewed the Board’s fiduciary duties in connection with its consideration of the proposed transaction. Representatives of Cravath reviewed with the Board the terms of the proposed merger agreement, including the terms of the “no shop” provisions and interim operating

covenants. Following additional discussion and consideration of the proposed merger agreement and the Merger and the other transactions contemplated by the proposed merger agreement, the Board recessed and the Compensation Committee of the Board convened and unanimously approved certain employment compensation and other employee benefit arrangements with respect to the employees of the Company in connection with the proposed merger agreement, including the treatment of Company equity awards. Following such approval by the Compensation Committee of the Board, the Board reconvened and unanimously (i) approved the Merger Agreement and declared that the Merger Agreement, the Merger and the other transactions contemplated by the Merger Agreement were advisable and fair to, and in the best interests of, the Company and its stockholders, (ii) authorized and approved the execution, delivery and performance by the Company of the Merger Agreement and the consummation of the transactions contemplated thereby, (iii) directed that the adoption of the Merger Agreement be submitted to a vote of the Company’s stockholders at a special meeting of the Company’s stockholders and (iv) resolved to recommend that the Company’s stockholders approve the adoption of the Merger Agreement and approve the Merger.

Following the conclusion of the Board meeting, the parties executed and delivered the Merger Agreement on August 7, 2022.

On August 8, 2022, prior to the opening of trading on the Nasdaq and the New York Stock Exchange, the parties issued a joint press release announcing the transaction.

The Board has unanimously: (a) determined that the Merger Agreement, the Merger and the other transactions contemplated thereby are advisable and fair to, and in the best interests of, GBT and its stockholders; (b) approved the Merger Agreement, the Merger and the other transactions contemplated thereby, including the execution, delivery and performance of the Merger Agreement and the consummation of the transactions contemplated thereby, including the Merger; (c) resolved to recommend that GBT stockholders adopt the Merger Agreement; and (d) directed that the adoption of the Merger Agreement be submitted for consideration by GBT stockholders at the Special Meeting.

The Board unanimously recommends that you vote: (1) “FOR” the adoption of the Merger Agreement; (2) “FOR” the Compensation Proposal; and (3) “FOR” the adjournment of the Special Meeting, if necessary or appropriate, to solicit additional proxies if there are insufficient votes to adopt the Merger Agreement at the time of the Special Meeting.

As described above in the section entitled “—Background of the Merger”, prior to and in reaching its unanimous determination to authorize and approve the Merger Agreement, the Merger and the other transactions contemplated by the Merger Agreement, declare the Merger advisable and in the best interests of the Company and stockholders of the Company and recommend that the Company’s stockholders approve the Merger, the Board consulted with and received the advice of its financial advisors and outside counsel, discussed certain issues with the Company’s management and considered a variety of factors weighing positively in favor of the Merger, the Merger Agreement and the transactions contemplated thereby, including, among other things, the following non-exhaustive list of material factors (not necessarily in order of relative importance):

In the course of its deliberations, the Board also considered a variety of risks and other countervailing factors related to the Merger Agreement and the Merger, including the following material factors:

The Board concluded that the uncertainties, risks and potentially negative factors relevant to the Merger were outweighed by the potential benefits of the Merger.

In addition to considering the factors described above, the Board also considered that some of GBT’s directors and executive officers have interests that may be different from, or in addition to, the interests of GBT stockholders generally. The Board was aware of these interests and considered them at the time it approved the Merger Agreement and made its recommendation to GBT stockholders. For more information, please see the section of this proxy statement entitled “—Interests of GBT’s Directors and Executive Officers in the Merger”. The foregoing discussion of the information and factors considered by the Board is not intended to be exhaustive, but includes the material positive and negative factors considered by the Board. In view of the wide variety of factors considered in connection with its evaluation of the Merger Agreement and the transactions contemplated by the Merger Agreement, including the Merger, and the complexity of these matters, the Board did not find it practicable to, and did not, quantify or otherwise assign relative weights to the specific factors considered in reaching its determination and recommendation. In addition, individual directors may have given different weights to different factors. The Board did not undertake to make any specific determination as to whether, or to what extent, any factor, or any particular aspect of any factor, supported or did not support its ultimate determination. The Board based its unanimous recommendation on the totality of the information presented, including the factors described above. This explanation of the reasoning of the Board and certain information presented in this section is forward-looking in nature and should be read in light of the factors set forth in the section of this proxy statement entitled “Cautionary Note Regarding Forward-Looking Statements”.

Pursuant to an engagement letter, the Company retained J.P. Morgan as one of its financial advisors in connection with the proposed Merger.

At the meeting of the Board on August 7, 2022, J.P. Morgan rendered its oral opinion to the Board that, as of such date and based upon and subject to the factors and assumptions set forth in its opinion, the Merger Consideration to be paid to GBT stockholders in the proposed Merger was fair, from a financial point of view, to such holders. J.P. Morgan has confirmed its August 7, 2022 oral opinion by delivering its written opinion to the Board, dated August 7, 2022, that, as of such date, the Merger Consideration to be paid to GBT stockholders in the proposed Merger was fair, from a financial point of view, to such holders.

The full text of the written opinion of J.P. Morgan, dated August 7, 2022, which sets forth, among other things, the assumptions made, matters considered and limits on the review undertaken, is attached as Annex B to this proxy statement and is incorporated herein by reference. The summary of the opinion of J.P. Morgan set forth in this proxy statement is qualified in its entirety by reference to the full text of such opinion. GBT stockholders are urged to read the opinion in its entirety. J.P. Morgan’s written opinion was addressed to the Board (in its capacity as such) in connection with and for the purposes of its evaluation of the proposed Merger, was directed only to the Merger Consideration to be paid in the Merger and did not address any other aspect of the Merger. J.P. Morgan expressed no opinion as to the fairness of any consideration to the holders of any other

class of securities, creditors or other constituencies of the Company or as to the underlying decision by the Company to engage in the proposed Merger. The issuance of J.P. Morgan’s opinion was approved by a fairness committee of J.P. Morgan. The summary of the opinion of J.P. Morgan set forth in this proxy statement is qualified in its entirety by reference to the full text of such opinion. The opinion does not constitute a recommendation to any GBT stockholder as to how such stockholder should vote with respect to the proposed Merger or any other matter.

In arriving at its opinions, J.P. Morgan, among other things:

In addition, J.P. Morgan held discussions with certain members of the management of the Company with respect to certain aspects of the Merger, and the past and current business operations of the Company, the financial condition and future prospects and operations of the Company and certain other matters J.P. Morgan believed necessary or appropriate to its inquiry.

In giving its opinion, J.P. Morgan relied upon and assumed the accuracy and completeness of all information that was publicly available or was furnished to or discussed with J.P. Morgan by the Company or otherwise reviewed by or for J.P. Morgan, and J.P. Morgan did not independently verify any such information or its accuracy or completeness (and did not assume any obligation to undertake any such independent verification). J.P. Morgan did not conduct and was not provided with any valuation or appraisal of any assets or liabilities, nor did J.P. Morgan evaluate the solvency of the Company or Parent under any state or federal laws relating to bankruptcy, insolvency or similar matters. In relying on financial analyses and forecasts provided to J.P. Morgan or derived therefrom, J.P. Morgan assumed that they were reasonably prepared based on assumptions reflecting the best currently available estimates and judgments by management as to the expected future results of operations and financial condition of the Company to which such analyses or forecasts relate. J.P. Morgan expressed no view as to such analyses or forecasts or the assumptions on which they were based. J.P. Morgan also assumed that the Merger and the other transactions contemplated by the Merger Agreement will be consummated as described in the Merger Agreement. J.P. Morgan also assumed that the representations and warranties made by the Company and Parent in the Merger Agreement and the related agreements were and will be true and correct in all respects material to its analysis. J.P. Morgan is not a legal, regulatory or tax expert and relied on the assessments made by advisors to the Company with respect to such issues. J.P. Morgan further assumed that all material governmental, regulatory or other consents and approvals necessary for the consummation of the Merger will be obtained without any adverse effect on the Company or on the contemplated benefits of the Merger.

The Management Projections were prepared by the Company’s management. The Company does not publicly disclose internal management projections of the type provided to J.P. Morgan in connection with J.P. Morgan’s analysis of the proposed Merger, and such projections were not prepared with a view toward public

disclosure. These projections were based on numerous variables and assumptions that are inherently uncertain and may be beyond the control of the Company’s management, including, without limitation, factors related to general economic and competitive conditions and prevailing interest rates. Accordingly, actual results could vary significantly from those set forth in such projections. For more information regarding the use of projections and other forward-looking statements, please refer to the section of this proxy statement below entitled “—Certain Financial Forecasts”.

J.P. Morgan’s opinion was necessarily based on economic, market and other conditions as in effect on, and the information made available to J.P. Morgan as of, the date of such opinion. J.P. Morgan’s opinion noted that subsequent developments may affect J.P. Morgan’s opinion, and that J.P. Morgan does not have any obligation to update, revise, or reaffirm such opinion. J.P. Morgan’s opinion is limited to the fairness, from a financial point of view, of the Merger Consideration to be paid to GBT stockholders in the proposed Merger, and J.P. Morgan has expressed no opinion as to the fairness of any consideration to the holders of any other class of securities, creditors or other constituencies of the Company or the underlying decision by the Company to engage in the Merger. Furthermore, J.P. Morgan expressed no opinion with respect to the amount or nature of any compensation to any officers, directors, or employees of any party to the proposed Merger, or any class of such persons relative to the Merger Consideration in the proposed Merger or with respect to the fairness of any such compensation.

The terms of the Merger Agreement, including the Merger Consideration, were determined through arm’s length negotiations between the Company and Parent, and the decision to enter into the Merger Agreement was solely that of the Board. J.P. Morgan’s opinion and financial analyses were only one of the many factors considered by the Board in its evaluation of the proposed Merger and should not be viewed as determinative of the views of the Board or management with respect to the proposed Merger or the Merger Consideration.

In accordance with customary investment banking practice, J.P. Morgan employed generally accepted valuation methodology in rendering its opinion to the Board on August 7, 2022 and contained in the presentation delivered to the Board on such date in connection with the rendering of such opinion. The summary below does not purport to be a complete description of the analyses or data presented by J.P. Morgan. Some of the summaries of the financial analyses include information presented in tabular format. The tables are not intended to stand alone, and in order to more fully understand the financial analyses used by J.P. Morgan, the tables must be read together with the full text of each summary. Considering the data set forth below without considering the full narrative description of the financial analyses, including the methodologies and assumptions underlying the analyses, could create a misleading or incomplete view of J.P. Morgan’s analyses.

Median FV/2026E Revenue Multiple = 3.5x

These companies were selected, among other reasons, because they are publicly traded companies with operations and business that, for the purposes of J.P. Morgan’s analysis, J.P. Morgan considered to be similar to those of the Company. However, certain of these companies may have characteristics that are materially different

from those of the Company. The analyses necessarily involve complex considerations and judgments concerning differences in financial and operational characteristics of the companies involved and other factors that could affect the selected companies differently than they would affect the Company.

Using publicly available information, J.P. Morgan calculated the multiple of the firm value (“FV”) for the Company and the selected companies (calculated as equity value, plus or minus, as applicable net debt or net cash) to the analyst consensus estimates for calendar year 2026 revenues for the applicable company (the “FV/2026E Revenue Multiple”).

Based on the above analysis, J.P. Morgan selected a FV/2026E Revenue Multiple reference range for the Company of 1.1x to 5.2x. J.P. Morgan then applied such reference range to the Company’s projected revenue for the calendar year 2026 provided in the Management Forecasts. The analysis indicated a range of implied per share equity value for the GBT common stock (rounded to the nearest $0.25) of approximately $21.25 to $88.50, which J.P. Morgan compared to the implied per share equity value of the Merger Consideration to be paid to GBT stockholders of $68.50.

Median FV/4-Year Forward Revenue Multiple = 3.5x

None of the selected transactions reviewed was identical to the proposed Merger. However, the selected transactions were chosen because certain aspects of the transactions, for purposes of J.P. Morgan’s analysis, may be considered similar to the proposed Merger. The analyses necessarily involve complex considerations and judgments concerning differences in financial and operational characteristics of the companies involved and other factors that could affect the transactions differently than they would affect the proposed Merger.

Using publicly available information, J.P. Morgan calculated, for each selected transaction, the multiple of the target company’s FV implied in the relevant transaction to the target company’s estimated forward revenue for the fourth year following the announcement of the applicable transaction (the “FV/4-Year Forward Revenue Multiple”).

Based on the above analysis, J.P. Morgan selected a FV/4-Year Forward Revenue Multiple reference range for the Company of 2.6x to 5.4x. J.P. Morgan then applied such reference range to the Company’s projected revenue for the twelve-month period ending September 30, 2026, $1.2 billion, which amount was provided by the management of the Company. The analysis indicated a range of implied per share equity value for the GBT common stock (rounded to the nearest $0.25) of approximately $44.25 to $83.75, which J.P. Morgan compared to the implied per share equity value of the Merger Consideration to be paid to GBT stockholders.

for corporate overhead and other unallocated expenses based on guidance provided by the Company’s management, to estimates of the unlevered free cash flow of the Company during calendar year 2042 as set forth in the Management Forecasts. The unlevered free cash flows and the range of terminal values were then discounted to present values as of September 30, 2022 using a range of discount rates from 10.5% to 13.5%, which were chosen by J.P. Morgan based upon an analysis of the weighted average cost of capital of the Company. The present value of the unlevered free cash flow estimates and the range of terminal values were then adjusted by adding net cash as of September 30, 2022, $351 million, which estimate was provided by the management of the Company. This analysis indicated a range of implied equity values for the Company, which J.P. Morgan divided by the number of outstanding shares of GBT common stock, calculated on a fully-diluted basis and adjusted for the Company’s assumed future equity raise of $200 million in gross proceeds in 2023, to derive a range of implied per share equity value for the GBT common stock (rounded to the nearest $0.25) of approximately $52.25 and $65.50, which J.P. Morgan compared to the implied per share equity value of the Merger Consideration to be paid to GBT stockholders of $68.50.

Analyses based upon forecasts of future results are inherently uncertain, as they are subject to numerous factors or events beyond the control of the parties and their advisors. Accordingly, forecasts and analyses used or made by J.P. Morgan are not necessarily indicative of actual future results, which may be significantly more or less favorable than suggested by those analyses. Moreover, J.P. Morgan’s analyses are not and do not purport to be appraisals or otherwise reflective of the prices at which businesses actually could be acquired or sold. None of the selected companies reviewed as described in the above summary is identical to the Company, and none of the selected transactions reviewed was identical to the Merger. However, the companies selected were chosen because they are publicly traded companies with operations and businesses that, for purposes of J.P. Morgan’s analysis, may be considered similar to those of the Company. The transactions selected were similarly chosen because their participants, size and other factors, for purposes of J.P. Morgan’s analysis, may be considered similar to the Merger. The analyses necessarily involve complex considerations and judgments concerning differences in financial and operational characteristics of the companies involved and other factors that could affect the companies compared to the Company and the transactions compared to the Merger.

As a part of its investment banking business, J.P. Morgan and its affiliates are continually engaged in the valuation of businesses and their securities in connection with mergers and acquisitions, investments for passive and control purposes, negotiated underwritings, secondary distributions of listed and unlisted securities, private placements, and valuations for corporate and other purposes. J.P. Morgan was selected to advise the Company with respect to the Merger and deliver an opinion to the Board with respect to the Merger on the basis of, among other things, such experience and its qualifications and reputation in connection with such matters and its familiarity with the Company and the industries in which it operates.

For financial advisory services rendered in connection with the Merger (including the delivery of its opinion), the Company will pay J.P. Morgan an aggregate fee of, approximately, $53,200,000, of which $2,000,000 became payable upon public announcement of the execution of the Merger Agreement with respect to a Merger and the remainder of which is payable upon the consummation of the Merger. In addition, the Company has agreed to reimburse J.P. Morgan for its expenses incurred in connection with its services, including the fees and disbursements of counsel, and will indemnify J.P. Morgan against certain liabilities arising out of J.P. Morgan’s engagement. During the two years preceding the date of J.P. Morgan’s opinion, neither J.P. Morgan nor its affiliates have had any other material financial advisory or other material commercial or investment banking relationships with the Company. During the two years preceding the date of J.P. Morgan’s opinion, J.P. Morgan and its affiliates have had commercial or investment banking relationships with Parent, for which J.P. Morgan and such affiliates have received customary compensation. Such services during such period have included acting as joint lead arranger and joint bookrunner on Parent’s credit facility in November 2021 and joint lead bookrunner on Parent’s offering of debt securities in August 2021. In addition, J.P. Morgan’s commercial banking affiliate is an agent bank and a lender under outstanding credit facilities of Parent, for which it receives customary compensation or other financial benefits. During the two-year period preceding delivery of its opinion on August 7, 2022, the aggregate fees recognized by J.P. Morgan from Parent were approximately $14 million. In addition, J.P. Morgan and its affiliates hold, on a proprietary basis, less than 1% of the outstanding common stock of each of the Company and Parent. In the ordinary course of their businesses, J.P. Morgan and its affiliates may actively trade the debt and equity securities or financial instruments (including derivatives, bank loans or other obligations) of the Company or Parent for their own accounts or for the accounts of customers and, accordingly, they may at any time hold long or short positions in such securities or other financial instruments.

On August 7, 2022, Centerview rendered to the Board its oral opinion, subsequently confirmed in a written opinion dated August 7, 2022, that, as of such date and based upon and subject to various assumptions made, procedures followed, matters considered and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion, the Merger Consideration to be paid to the holders of shares of GBT common stock (other than (i) Appraisal Shares (as defined in the Merger Agreement) and (ii) shares of GBT common stock owned directly by the Company, Parent or any of their respective wholly owned subsidiaries (the shares referred to in clauses (i) and (ii), together with any shares of GBT common stock held by any affiliate of the Company or Parent, “Excluded Shares”) pursuant to the Merger Agreement was fair, from a financial point of view, to such holders.

The full text of Centerview’s written opinion, dated August 7, 2022, which describes the assumptions made, procedures followed, matters considered and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion, is attached as Annex C and is incorporated herein by reference. The summary of the written opinion of Centerview set forth below is qualified in its entirety by reference to the full text of Centerview’s written opinion attached as Annex C. Centerview’s financial advisory services and opinion were provided for the information and assistance of the Board (in the directors’ capacity as directors and not in any other capacity) in connection with and for purposes of its consideration of the Merger and the other transactions contemplated by the Merger Agreement (which we refer to, collectively, as the “Transaction”) and Centerview’s opinion only addressed the fairness, from a financial point of view, as of the date thereof, to the holders of shares of GBT common stock (other than Excluded Shares) of the Merger Consideration to be paid to such holders pursuant to the Merger Agreement. Centerview’s opinion did not address any other term or aspect of the Merger Agreement or the Transaction and does not constitute a recommendation to any GBT stockholder or any other person as to how such stockholder or other person should vote with respect to the Merger or otherwise act with respect to the Transaction or any other matter.

The full text of Centerview’s written opinion should be read carefully in its entirety for a description of the assumptions made, procedures followed, matters considered, and qualifications and limitations upon the review undertaken by Centerview in preparing its opinion.

In connection with rendering the opinion described above and performing its related financial analyses, Centerview reviewed, among other things:

Centerview also participated in discussions with members of the senior management and representatives of the Company regarding their assessment of the Internal Data. In addition, Centerview reviewed publicly available financial and stock market data, including valuation multiples, for the Company and compared that data with similar data for certain other companies, the securities of which are publicly traded, in lines of business that Centerview deemed relevant. Centerview also compared certain of the proposed financial terms of the Transaction with the financial terms, to the extent publicly available, of certain other transactions that Centerview deemed relevant, and conducted such other financial studies and analyses and took into account such other information as Centerview deemed appropriate.

Centerview assumed, without independent verification or any responsibility therefor, the accuracy and completeness of the financial, legal, regulatory, tax, accounting and other information supplied to, discussed with or reviewed by Centerview for purposes of its opinion and, with the Company’s consent, Centerview relied upon such information as being complete and accurate. In that regard, Centerview assumed, at the Company’s direction, that the Internal Data (including, without limitation, the Management Forecasts) were reasonably prepared on bases reflecting the best currently available estimates and judgments of the management of the Company as to the matters covered thereby and Centerview relied, at the Company’s direction, on the Internal Data for purposes of Centerview’s analysis and opinion. Centerview expressed no view or opinion as to the Internal Data or the assumptions on which it was based. In addition, at the Company’s direction, Centerview did not make any independent evaluation or appraisal of any of the assets or liabilities (contingent, derivative, off-balance-sheet or otherwise) of the Company, nor was Centerview furnished with any such evaluation or appraisal, and was not asked to conduct, and did not conduct, a physical inspection of the properties or assets of the Company. Centerview assumed, at the Company’s direction, that the final executed Merger Agreement would not differ in any respect material to Centerview’s analysis or opinion from the Draft Merger Agreement reviewed by Centerview. Centerview also assumed, at the Company’s direction, that the Transaction will be consummated on the terms set forth in the Merger Agreement and in accordance with all applicable laws and other relevant documents or requirements, without delay or the waiver, modification or amendment of any term, condition or agreement, the effect of which would be material to Centerview’s analysis or Centerview’s opinion and that, in the course of obtaining the necessary governmental, regulatory and other approvals, consents, releases and waivers for the Transaction, no delay, limitation, restriction, condition or other change will be imposed, the effect of which would be material to Centerview’s analysis or Centerview’s opinion. Centerview did not evaluate and did not express any opinion as to the solvency or fair value of the Company, or the ability of the Company to

pay its obligations when they come due, or as to the impact of the Transaction on such matters, under any state, federal or other laws relating to bankruptcy, insolvency or similar matters. Centerview is not a legal, regulatory, tax or accounting advisor, and Centerview expressed no opinion as to any legal, regulatory, tax or accounting matters.

Centerview’s opinion expressed no view as to, and did not address, the Company’s underlying business decision to proceed with or effect the Transaction, or the relative merits of the Transaction as compared to any alternative business strategies or transactions that might be available to the Company or in which the Company might engage. Centerview’s opinion was limited to and addressed only the fairness, from a financial point of view, as of the date of Centerview’s written opinion, to the holders of shares of GBT common stock (other than Excluded Shares) of the Merger Consideration to be paid to such holders pursuant to the Merger Agreement. For purposes of its opinion, Centerview was not asked to, and Centerview did not, express any view on, and its opinion did not address, any other term or aspect of the Merger Agreement or the Transaction, including, without limitation, the structure or form of the Transaction, or any other agreements or arrangements contemplated by the Merger Agreement or entered into in connection with or otherwise contemplated by the Transaction, including, without limitation, the fairness of the Transaction or any other term or aspect of the Transaction to, or any consideration to be received in connection therewith by, or the impact of the Transaction on, the holders of any other class of securities, creditors or other constituencies of the Company or any other party. In addition, Centerview expressed no view or opinion as to the fairness (financial or otherwise) of the amount, nature or any other aspect of any compensation to be paid or payable to any of the officers, directors or employees of the Company or any party, or class of such persons in connection with the Transaction, whether relative to the Merger Consideration to be paid to the holders of shares of GBT common stock pursuant to the Merger Agreement or otherwise. Centerview’s opinion was necessarily based on financial, economic, monetary, currency, market and other conditions and circumstances as in effect on, and the information made available to Centerview as of, the date of Centerview’s written opinion, and Centerview does not have any obligation or responsibility to update, revise or reaffirm its opinion based on circumstances, developments or events occurring after the date of Centerview’s written opinion. Centerview’s opinion does not constitute a recommendation to any GBT stockholder or any other person as to how such stockholder or other person should vote with respect to the Merger or otherwise act with respect to the Transaction or any other matter. Centerview’s financial advisory services and its written opinion were provided for the information and assistance of the Board (in the directors’ capacity as directors and not in any other capacity) in connection with and for purposes of its consideration of the Transaction. The issuance of Centerview’s opinion was approved by the Centerview Partners LLC Fairness Opinion Committee.

The following is a summary of the material financial analyses prepared and reviewed with the Board in connection with Centerview’s opinion, dated August 7, 2022. The summary set forth below does not purport to be a complete description of the financial analyses performed or factors considered by, and underlying the opinion of, Centerview, nor does the order of the financial analyses described represent the relative importance or weight given to those financial analyses by Centerview. Centerview may have deemed various assumptions more or less probable than other assumptions, so the reference ranges resulting from any particular portion of the analyses summarized below should not be taken to be Centerview’s view of the actual value of the Company. Some of the summaries of the financial analyses set forth below include information presented in tabular format. In order to fully understand the financial analyses, the tables must be read together with the text of each summary, as the tables alone do not constitute a complete description of the financial analyses performed by Centerview. Considering the data in the tables below without considering all financial analyses or factors or the full narrative description of such analyses or factors, including the methodologies and assumptions underlying such analyses or factors, could create a misleading or incomplete view of the processes underlying Centerview’s financial analyses and its opinion. In performing its analyses, Centerview made numerous assumptions with respect to industry performance, general business and economic conditions and other matters, many of which are beyond the control of the Company or any other parties to the Transaction. None of the Company, Parent, Merger Sub or Centerview or any other person assumes responsibility if future results are materially different from those discussed. Any estimates contained in these analyses are not necessarily indicative of actual values or predictive of future results or values, which may be significantly more or less favorable than as set forth below. In addition, analyses relating to the value of the Company do not purport to be appraisals or reflect the prices at which the Company

may actually be sold. Accordingly, the assumptions and estimates used in, and the results derived from, the financial analyses are inherently subject to substantial uncertainty. Except as otherwise noted, the following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before August 5, 2022 (the last trading day before the public announcement of the Transaction) and is not necessarily indicative of current market conditions.

Centerview reviewed certain financial information of the Company and compared it to corresponding financial information of certain publicly traded biopharmaceutical companies that Centerview selected based on its experience and professional judgment (which companies are referred to as the “selected companies” in this summary of Centerview’s opinion). Although none of the selected companies is directly comparable to the Company, the companies listed below were chosen by Centerview because, among other reasons, they are publicly traded biopharmaceutical companies with certain business, operational and/or financial characteristics that, for purposes of Centerview’s analysis, may be considered similar to those of the Company.

However, because each of the selected companies has business, operational and/or financial characteristics that differ significantly from those of the Company, Centerview believed that it was inappropriate to, and therefore did not, rely solely on the quantitative results of the selected public company analysis. Accordingly, Centerview also made qualitative judgments, based on its experience and professional judgment, concerning differences between the business, operational and/or financial characteristics of the Company and the selected companies that could affect the public trading values of each in order to provide a context in which to consider the results of the quantitative analysis.

Using publicly available information obtained from SEC filings and other data sources as of August 5, 2022, Centerview calculated, for each selected company, such company’s enterprise value (calculated as the equity value (determined using the treasury stock method and taking into account outstanding in-the-money options, warrants, restricted stock units, performance stock units and other convertible securities) plus the book value of debt less cash and cash equivalents as a multiple of Wall Street research analyst consensus estimated revenue for calendar year 2026 (“EV/2026E Revenue Trading Multiple”).

The selected companies are summarized below:

Median EV/2026E Revenue Trading Multiple = 3.6x

Based on this analysis and other considerations that Centerview deemed relevant in its professional judgment and experience, Centerview selected a reference range of EV/2026E Revenue Trading Multiples of 2.00x to 4.25x to apply to the Company’s estimated calendar year risk-adjusted 2026 net revenue as set forth in the Management Forecasts and to Wall Street research analyst consensus estimated net revenue for the Company for calendar year 2026. In selecting these ranges of EV/2026E Revenue Trading Multiples, Centerview made qualitative judgments based on its experience and professional judgment concerning differences between the business, operational and/or financial characteristics of the Company and the selected companies that could affect their public trading values in order to provide a context in which to consider the results of the quantitative analysis. Applying this range of EV/2026E Revenue Trading Multiples to the Company’s estimated calendar year risk-adjusted 2026 net revenue as set forth in the Management Forecasts of $1.293 billion under the Management Forecasts, and to Wall Street research analyst consensus estimated net revenue for the Company for calendar year 2026 of $912 million, and adding to such amounts the Company’s estimated net cash as of September 30, 2022 provided by the Company management as set forth in the Internal Data, and dividing the results of the foregoing calculations by the number of fully diluted outstanding shares of GBT common stock (determined using the treasury stock method and taking into account outstanding in-the-money options, restricted stock units, performance stock units and shares issuable upon conversion of the Convertible Notes (as defined in the section of this proxy statement entitled “Proposal 1: Adoption of the Merger Agreement—Capped Call Transactions”), if

applicable), based on information provided by the Company management as of August 4, 2022 as set forth in the Internal Data. For the purposes of Centerview’s analysis, net cash and fully diluted outstanding shares of GBT common stock varied depending on whether the Convertible Notes were deemed to be in-the-money (at implied equity values per share above $31.75) or out-of-the-money (at implied equity values per share at or below $31.75). This analysis resulted in an implied per share equity value range for shares of GBT common stock of approximately $35.85 to $71.65 and $25.45 to $52.90, respectively, rounded to the nearest $0.05. Centerview then compared these ranges to the Merger Consideration of $68.50 per share to be paid to the holders of shares of GBT common stock (other than Excluded Shares) pursuant to the Merger Agreement.

Centerview reviewed and analyzed certain information relating to the following selected transactions involving biopharmaceutical companies (which transactions are referred to as the “selected transactions” in this summary of Centerview’s opinion) that Centerview, based on its experience and professional judgment, deemed relevant to consider in relation to the Company and the Transaction. Although none of the selected transactions is directly comparable to the Transaction, these transactions were selected, among other reasons, because they have certain business, operational and/or financial characteristics that, for purposes of Centerview’s analysis, may be considered similar to the Transaction. The reasons for and the circumstances surrounding each of the selected precedent transactions analyzed were diverse and there are inherent differences in the business, operational and/or financial conditions and prospects of the Company and the companies included in the selected precedent transactions analysis. This analysis involved complex considerations and qualitative judgments concerning differences in business, operational and/or financial characteristics and other factors that could affect the public trading, acquisition or other values of the target companies in the selected transactions and the Company.

Using publicly available information obtained from SEC filings and other data sources as of the time of the announcement of the selected transactions, Centerview calculated, for each selected transaction, the transaction value (calculated as the offer value (determined using the treasury stock method and taking into account outstanding in-the-money options, warrants, restricted stock units, performance stock units and other convertible securities), plus the book value of debt and certain liabilities less cash and cash equivalents and excluding any contingent consideration) implied for each target company based on the consideration payable in the applicable selected transaction) as a multiple of the target company’s Wall Street research analyst consensus estimated four-year forward net revenue at the time of the transaction announcement (“Four-Year Forward Revenue Multiple”).

The selected transactions considered in this analysis are summarized below:

Median Transaction Value/4-Year Forward Revenue Multiple = 3.6x

Based on this analysis and other considerations that Centerview deemed relevant in its experience and professional judgment, related to, among other things, differences in the business, operational and/or financial conditions and prospects of the Company and the companies included in the selected precedent transactions analysis, Centerview selected a reference range of Four-Year Forward Revenue Multiples of 3.00x to 4.50x derived from the selected precedent transactions. Centerview applied this reference range of Four-Year Forward Revenue Multiples to Wall Street research analyst consensus estimated four-year forward net revenue of $874 million, and added to it the Company’s estimated net cash as of September 30, 2022, adjusted for an estimated $77 million in change of control payments and prepayment penalties under the Company’s outstanding

term loan payable in connection with the Transaction, provided by the Company management as set forth in the Internal Data, and divided the result of the foregoing calculations by the Company’s fully diluted outstanding shares of GBT common stock (determined using the treasury stock method and taking into account outstanding in-the-money options, restricted stock units, performance stock units and shares issuable upon conversion of the Convertible Notes, including additional shares of GBT common stock issued as a result of the make-whole with respect to the Convertible Notes, if applicable) based on information provided by the Company management as of August 4, 2022 as set forth in the Internal Data. For the purposes of Centerview’s analysis, net cash and fully diluted shares varied depending on whether the Convertible Notes were deemed to be in-the-money (at implied equity values per share above $31.75) or out-of-the-money (at implied equity values per share at or below $31.75). This analysis resulted in an implied per share equity value range for shares of GBT common stock of approximately $34.55 to $50.35, rounded to the nearest $0.05. Centerview then compared this range to the Merger Consideration of $68.50 per share to be paid to the holders of shares of GBT common stock (other than Excluded Shares) pursuant to the Merger Agreement.

Centerview performed a discounted cash flow analysis of the Company based on the Internal Data. A discounted cash flow analysis is a traditional valuation methodology used to derive a valuation of an asset or set of assets by calculating the “present value” of estimated future cash flows of the asset or set of assets. “Present value” refers to the current value of future cash flows or amounts and is obtained by discounting those future cash flows or amounts by a discount rate that takes into account macroeconomic assumptions and estimates of risk, the opportunity cost of capital, expected returns and other appropriate factors.

In performing this analysis, Centerview calculated a range of equity values for shares of GBT common stock by (a) discounting to present value as of September 30, 2022 using discount rates ranging from 10.5% to 12.5% (reflecting Centerview’s analysis of the Company’s weighted average cost of capital) and using a mid-year convention: (i) the forecasted risk-adjusted, after-tax unlevered free cash flows of the Company over the period beginning on October 1, 2022 and ending on December 31, 2042, utilized by Centerview based on the Management Forecasts, (ii) an implied terminal value of the Company, calculated by Centerview by assuming that unlevered free cash flows would decline in perpetuity after December 31, 2042 (with the exception of cash flows associated with research assets and corporate overhead and other unallocated expenses), based on guidance provided by the Company management, and (iii) tax savings from usage of the Company’s federal net operating losses of $1.081 billion as of September 30, 2022 and the Company’s future losses and (b) adding to the foregoing results the Company’s estimated net cash as of September 30, 2022, $351 million (adjusted for the conversion of the Convertible Notes, if applicable), which amount was provided by the Company management as set forth in the Internal Data, and an assumed equity raise of $200 million in 2023 as set forth in the Internal Data. Centerview divided the result of the foregoing calculations by the Company’s fully diluted outstanding shares of GBT common stock (determined using the treasury stock method and taking into account outstanding in-the-money options, restricted stock units, performance stock units and shares issuable upon conversion of the Convertible Notes, if applicable), based on information provided by the Company management as of August 4, 2022 as set forth in the Internal Data. This analysis resulted in a range of implied equity values per share of GBT common stock of $56.35 to $65.25, rounded to the nearest $0.05. Centerview then compared this range to the Merger Consideration of $68.50 per share to be paid to the holders of shares of GBT common stock (other than Excluded Shares) pursuant to the Merger Agreement.

Centerview noted for the Board certain additional factors solely for informational purposes, including, among other things, the following:

The preparation of a financial opinion is a complex analytical process involving various determinations as to the most appropriate and relevant methods of financial analysis and the application of those methods to the particular circumstances and, therefore, a financial opinion is not readily susceptible to summary description. In arriving at its opinion, Centerview did not draw, in isolation, conclusions from or with regard to any factor or analysis that it considered. Rather, Centerview made its determination as to fairness on the basis of its experience and professional judgment after considering the results of all of the analyses.

Centerview’s financial analyses and opinion were only one of many factors taken into consideration by the Board in its evaluation of the Transaction. Consequently, the analyses described above should not be viewed as determinative of the views of the Board or management of the Company with respect to the Merger Consideration or as to whether the Board would have been willing to determine that a different consideration was fair. The consideration for the Transaction was determined through arm’s-length negotiations between the Company and Parent and was approved by the Board. Centerview provided advice to the Company during these negotiations. Centerview did not, however recommend any specific amount of consideration to the Company or the Board or that any specific amount of consideration constituted the only appropriate consideration for the Transaction.

Centerview is a securities firm engaged directly and through affiliates and related persons in a number of investment banking, financial advisory and merchant banking activities. In the two years prior to the date of its written opinion, except for Centerview’s current engagement, Centerview has not been engaged to provide financial advisory or other services to the Company, and Centerview has not received any compensation from the Company during such period. In the two years prior to the date of its written opinion, Centerview was engaged to provide financial advisory services unrelated to the Merger to Parent, including in connection with Parent’s acquisition of Arena Pharmaceuticals, Inc. in 2022 and certain other strategic matters. Centerview received between $20 million and $30 million in aggregate compensation from Parent for work performed during such period. Centerview may provide financial advisory and other services to or with respect to the Company or Parent or their respective affiliates in the future, for which Centerview may receive compensation. Certain (i) of Centerview’s and its affiliates’ directors, officers, members and employees, or family members of such persons, (ii) of Centerview’s affiliates or related investment funds and (iii) investment funds or other persons in which any of the foregoing may have financial interests or with which they may co-invest, may at any time acquire, hold, sell or trade, in debt, equity and other securities or financial instruments (including derivatives, bank loans or other obligations) of, or investments in, the Company, Parent or any of their respective affiliates, or any other party that may be involved in the Transaction.

The Board selected Centerview as its financial advisor in connection with the Transaction based on Centerview’s knowledge of the biopharmaceutical industry. Centerview is an internationally recognized investment banking firm that has substantial experience in transactions similar to the Transaction.

In connection with Centerview’s services as a financial advisor to the Board, the Company has agreed to pay Centerview an aggregate fee of approximately $42 million, $2 million of which was payable upon the rendering of Centerview’s opinion and $40 million of which is payable contingent upon consummation of the Transaction. In addition, the Company has agreed to reimburse certain of Centerview’s expenses arising, and to indemnify Centerview against certain liabilities that may arise, out of Centerview’s engagement.

On December 14, 2021, in connection with the pricing of GBT’s 1.875% Convertible Senior Notes due 2028 (which we refer to as the “Convertible Notes”), GBT entered into privately negotiated capped call transactions (which we refer to as the “Base Capped Call Transactions”) with each of Jefferies International Limited, Mizuho Securities USA, LLC, as agent for Mizuho Markets Americas LLC, RBC Capital Markets, LLC, as agent for Royal Bank of Canada, and Wells Fargo Bank National Association (which we refer to as the “Capped Call Counterparties”). On December 15, 2021, in connection with the initial purchasers’ exercise of their option to purchase additional Convertible Notes, GBT entered into additional capped call transactions with each of the Capped Call Counterparties (which we refer to as the “Additional Capped Call Transactions” and, together with the Base Capped Call Transactions, the “Capped Call Transactions”).

The Capped Call Transactions initially covered, subject to customary anti-dilution adjustments, the number of shares of GBT common stock that initially underlie the Convertible Notes. The strike price of the Capped Call Transactions is $31.7475 per share of GBT common stock, and the cap price of the Capped Call Transactions is $49.80 per share of GBT common stock, and is subject to certain adjustments under the terms of the Capped Call Transactions. The Capped Call Transactions are expected generally to reduce potential dilution to GBT common stock upon conversion of the Convertible Notes and/or offset the potential cash payments that GBT could be required to make in excess of the principal amount of converted Convertible Notes, as the case may be, with such reduction and/or offset subject to a cap based on the cap price.

If the Merger is consummated, holders of the Convertible Notes may convert their Convertible Notes, and the consummation of the Merger is expected to result in the full termination of the Capped Call Transactions. The value received by the Company in connection with the termination or unwinding of the Capped Call Transactions would be determined by the Capped Call Counterparties based on the fair value of the Capped Call Transactions, which is contingent on a variety of factors including, but not limited to, volatility, spot price and liquidity of GBT common stock.

In addition, following the announcement of the Merger, the Capped Call Counterparties may adjust the terms of the applicable Capped Call Transactions on more than one occasion to reflect the economic effect of such announcement, including if such economic effect is material, and regardless of whether the Merger is consummated. Each Capped Call Counterparty shall, in good faith and in a commercially reasonable manner, in its capacity as calculation agent with respect to its Capped Call Transaction, determine whether such announcement has had a material economic effect on such Capped Call Transaction and may take into account a number of factors, including the date of the announcement (and the remaining term of its Capped Call Transaction at that time), the stock price of GBT common stock and changes in volatility, stock loan rate, liquidity and expected dividends of GBT common stock, in determining whether an adjustment to the cap price of its Capped Call Transaction is appropriate. Each Capped Call Counterparty may make additional adjustments to the cap price of its Capped Call Transaction following the announcement of a change to the Merger, including a withdrawal from, or the abandonment or discontinuation of, the Merger.

The indenture governing the Convertible Notes and the forms of confirmations containing the terms of the Capped Call Transactions were included as exhibits, in each case, to GBT’s Current Report on Form 8-K filed by GBT with the SEC on December 17, 2021. All references in this section of this proxy statement to share counts, conversion prices and strike prices may change from time to time in accordance with the terms of the relevant confirmations.

The Company does not, as a matter of course, publicly disclose forecasts or internal projections as to future performance, or results of operations, earnings or other results, due to, among other things, the inherent difficulty of predicting financial performance for future periods and the likelihood that the underlying assumptions and estimates may not be realized. In June 2022, in connection with the evaluation of a proposed transaction, at the

direction of the Board, senior management of the Company with the assistance of the Company’s financial advisors prepared certain preliminary non-public, unaudited prospective financial information for fiscal years 2022 through 2042. In July and August 2022, in the context of evaluating the proposals from Pfizer and other potential acquirors, GBT senior management with the assistance of the Company’s financial advisors updated such preliminary non-public, unaudited prospective financial information to take into account certain downward adjustments relating to, among other things, developments and business momentum, trends and forecasts, including developments relating to coverage, reimbursement and payor rules and policies applicable to, and pricing of, Oxbryta (which we refer to as the “Management Forecasts”).

GBT is including a summary of the Management Forecasts to provide GBT stockholders with access to information that was made available to the Board in connection with its evaluation of the Merger and the Merger Consideration. The Management Forecasts were not provided to Pfizer or any of the other potential acquirors.

The Board reviewed the Management Forecasts and, following discussions with GBT management, the Board authorized GBT’s financial advisors to use the Management Forecasts, or a subset thereof, for purposes of their respective financial analyses and fairness opinions summarized in the sections of this proxy statement entitled “—Opinion of J.P. Morgan” and “—Opinion of Centerview”. Management of the Company modeled the Management Forecasts based on its reasonable best estimates and assumptions with respect to the future financial performance of the Company on a standalone basis. The Management Forecasts were based upon certain financial, operating and commercial assumptions developed solely using the information available to management of the Company at the time the Management Forecasts were created.

The following table summarizes the Management Forecasts, as described above:

The Management Forecasts were prepared for internal use only and not for public disclosure and were provided to the Board for the purposes of GBT’s strategic review process. The Management Forecasts were also provided to and used by J.P. Morgan and Centerview, GBT’s financial advisors, for the purpose of performing financial analyses in connection with the strategic review process and for the purpose of evaluating the fairness of the Merger Consideration from a financial point of view.

The summary of the Management Forecasts is included in this proxy statement solely to give GBT stockholders access to certain financial forecasts that were made available to the Board, J.P. Morgan and Centerview and is not being included in this proxy statement to influence a GBT stockholder’s decision whether to vote for the Merger Agreement Proposal or for any other purpose.

The Management Forecasts were generated solely for internal use and not developed with a view toward public disclosure or with a view toward complying with the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of prospective financial data, published guidelines of the SEC regarding forward-looking statements or GAAP, but, in the view of GBT management, were reasonably prepared in good faith on a basis reflecting the best available estimates and judgments at the time of preparation, and presented as of the time of preparation. No independent registered public accounting firm provided any assistance in preparing the Management Forecasts. Accordingly, no independent registered public accounting firm has examined, compiled or otherwise performed any procedures with respect to the Management Forecasts or expressed any opinion or given any other form of assurance with respect thereto, and they assume no responsibility for the information contained in the Management Forecasts. The KPMG LLP report included in GBT’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021 relates solely to the historical financial information of GBT and to an assessment of GBT’s internal controls over financial reporting. Such reports do not extend to the Management Forecasts and should not be read to do so.

The inclusion of the Management Forecasts should not be regarded as an indication that GBT, Pfizer, their affiliates or financial advisors or any of their respective representatives or any other recipient of this information considered, or now considers, the Management Forecasts to be necessarily predictive of future results. There can be no assurance that the projected results will be realized or that actual results will not be materially lower or higher than estimated, whether or not the Merger is completed. None of GBT, Parent or their respective affiliates, officers, directors, advisors or other representatives can provide any assurance that actual results will not differ from the Management Forecasts, and, except as required by applicable law, none of GBT, Parent or their respective affiliates undertakes any obligation to update, or otherwise revise or reconcile, the Management Forecasts to reflect circumstances existing after the date the Management Forecasts were generated or to reflect the occurrence of future events even in the event that any or all of the assumptions underlying the Management Forecasts are shown to be inappropriate. None of GBT or its affiliates, officers, directors, advisors or other representatives has made or makes any representation to any GBT stockholder or other person regarding the information included in the Management Forecasts or GBT’s ultimate performance compared to the information contained in the Management Forecasts or that forecasted results will be achieved. GBT has made no representation to Parent, in the Merger Agreement or otherwise, concerning the Management Forecasts. The Management Forecasts are forward-looking statements. The assumptions and estimates underlying the Management Forecasts, all of which are difficult to predict and many of which are beyond the control of GBT, may not be realized. Neither GBT nor any of its affiliates assumes any responsibility to holders of shares of GBT common stock for the accuracy of this information. In particular, the Management Forecasts, while presented with numerical specificity necessarily, were based on numerous variables and assumptions that are inherently uncertain and are subject to a wide variety of significant business, economic, competitive and regulatory risks and uncertainties that could cause actual results to differ materially from those contained in the Management Forecasts. Because the Management Forecasts cover multiple years, by their nature, they become subject to greater uncertainty with each successive year and are unlikely to anticipate each circumstance that will have an effect on the commercial value of Oxbryta and the Company’s product candidates. As a result, there can be no assurance that the Management Forecasts accurately reflect future trends or accurately estimate the future market for Oxbryta and the Company’s product candidates. There can be no assurance of the approval, or timing of such approval, of any of the Company’s clinical-stage product candidates, and it is possible that other therapeutic scenarios will be preferable. Important factors that may affect actual results and results in the Management Forecasts not being achieved include, but are not limited to: risks and uncertainties relating to the COVID-19 pandemic, including the extent and duration of the impact on the Company’s business, the results of

the Company’s commercialization of Oxbryta, obtaining marketing approvals for Oxbryta in additional indications or in additional jurisdictions, the potential safety, efficacy or other therapeutic benefits of Oxbryta and the Company’s product candidates, maintaining the scope and extent of GBT’s intellectual property and regulatory protections, the timing of regulatory approval and launch, success of clinical testing, labeling, market uptake of the Company’s product candidates, the effects of healthcare reform, the effect of regulatory actions, availability of third-party reimbursement, impact of competitive products and pricing, the effect of regulatory actions, the effect of global economic conditions, fluctuations in foreign currency exchange rates, the cost and effect of changes in tax and other legislation and other risk factors described in GBT’s SEC filings, including GBT’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021 and our most recent Quarterly Report on Form 10-Q and Current Reports on Form 8-K, and described under the section below entitled “Cautionary Note Regarding Forward-Looking Statements”. The Management Forecasts also reflect assumptions as to certain business decisions that are subject to change.

Modeling and forecasting the future commercialization of products and clinical, pre-clinical and research stage product candidates is a highly speculative endeavor. In addition to the various limitations, risks and uncertainties described above, we also cannot assure you that the Company will obtain and maintain any of the regulatory approvals necessary for the commercialization of Oxbryta or its product candidates, or that the Company’s competitors will not commercialize products that are safer, more effective or more successfully marketed and sold than Oxbryta or any products that the Company may commercialize in the future. Some or all of the estimates and assumptions underlying the Management Forecasts may have changed since the date the Management Forecasts were prepared. The information set forth in the Management Forecasts is not fact and should not be relied upon as being necessarily indicative of future results. The Management Forecasts were developed on a standalone basis without giving effect to the Merger, and therefore the Management Forecasts do not give effect to the Merger or any changes to GBT’s operations or strategy that may be implemented after the consummation of the Merger, including cost synergies realized as a result of the Merger, or to any costs incurred in connection with the Merger. Furthermore, the Management Forecasts do not take into account the effect of any failure of the Merger to be completed and should not be viewed as accurate or continuing in that context.

The Management Forecasts contain certain non-GAAP financial measures that GBT management believes are helpful in understanding GBT’s past financial performance and future results. GBT management regularly uses a variety of financial measures that are not in accordance with GAAP for forecasting, budgeting and measuring financial performance. The non-GAAP financial measures are not meant to be considered in isolation or as a substitute for comparable GAAP measures. While GBT believes these non-GAAP financial measures provide meaningful information to help investors understand the operating results and to analyze GBT’s financial and business trends on a period-to-period basis, there are limitations associated with the use of these non-GAAP financial measures. These non-GAAP financial measures are not prepared in accordance with GAAP, are not reported by all of GBT’s competitors and may not be directly comparable to similarly titled measures of GBT’s competitors due to potential differences in the exact method of calculation. The SEC rules that would otherwise require a reconciliation of a non-GAAP financial measure to a GAAP financial measure do not apply to non-GAAP financial measures provided to a board of directors or a financial advisor in connection with a proposed business combination such as the Merger if the disclosure is included in a document such as this proxy statement. In addition, reconciliations of non-GAAP financial measures were not relied upon by the Board or GBT’s financial advisors in connection with their respective evaluations of the Merger. Accordingly, GBT has not provided a reconciliation of the non-GAAP financial measures included in the Management Forecasts to the relevant GAAP financial measures.

The Management Forecasts summarized in this section were prepared prior to the execution of the Merger Agreement and have not been updated to reflect any changes after the date they were prepared. THE COMPANY DOES NOT INTEND, AND UNDERTAKES NO OBLIGATION, TO UPDATE OR OTHERWISE REVISE THE PROJECTIONS TO REFLECT CIRCUMSTANCES EXISTING SINCE THEIR PREPARATION OR TO REFLECT THE OCCURRENCE OF FUTURE EVENTS, EVEN IN THE EVENT THAT ANY OR ALL OF THE ASSUMPTIONS UNDERLYING THE PROJECTIONS ARE NO LONGER APPROPRIATE. In light of the foregoing factors and the uncertainties inherent in the Management Forecasts, readers of this proxy statement are cautioned not to place undue reliance on the Management Forecasts.

GBT’s directors and executive officers have financial interests in the Merger that may be different from, or in addition to, the interests of GBT stockholders generally. The members of the Board were aware of and considered these interests in reaching the determination to approve the Merger Agreement and recommend that GBT stockholders vote their GBT common shares to adopt the Merger Agreement.

At the Effective Time, subject to all required withholding taxes, equity awards granted on or prior to the date of the Merger Agreement that remain outstanding as of immediately prior to the Effective Time will be treated as follows:

At the Effective Time, equity awards that may be granted to employees of the Company (including the executive officers) after the date of the Merger Agreement and prior to the Effective Time and that remain outstanding as of immediately prior to the Effective Time will be converted into cash awards (based on the Merger Consideration multiplied by the number of shares of GBT common stock subject to the applicable award immediately prior to the completion of the Merger) subject to the same vesting schedule applicable to the corresponding award. Upon an executive officer’s qualifying termination within one year following the completion of the Merger, subject to the execution of a release of claims in favor of Pfizer and the Company, any such awards would be subject to pro rata accelerated vesting based on the number of days elapsed from the grant date to the termination date relative to the total number of days in the vesting period.

The following table sets forth the number of Company Options, Company RSUs and Company PSUs held by each of the Company’s directors and executive officers as of August 15, 2022, the latest practicable date to determine such amounts before the filing of this proxy statement, and the cash amounts payable (on a pre-tax basis) in respect thereof. The amounts reflected in the table below exclude any grants that may be made following August 15, 2022 and any Company Options, Company RSUs and Company PSUs that are vested or are expected to vest in accordance with their terms prior to December 31, 2022 (the assumed date of the completion of the Merger solely for purposes of this transaction-related compensation disclosure). Company Options are valued based on the difference between the per share exercise price of such Company Option and the Merger Consideration of $68.50 per share. As a result, any Company Option included in the table below that has an exercise price that is greater than or equal to the Merger Consideration does not have any value for purposes of the table below. Company RSUs and Company PSUs (other than Stock Price PSUs) are valued based on the Merger Consideration of $68.50 per share. Stock Price PSUs will be forfeited upon the consummation of the Merger and, therefore, are excluded from the amounts listed in the below table. Payments in respect of all Company Options, Company RSUs and Company PSUs held by the Company’s directors and executive officers that were outstanding on the date of the Merger Agreement are “single-trigger” in that they will be paid upon the consummation of the Merger.

Each of the executive officers participates in the Company’s Amended and Restated Severance and Change in Control Policy, which we refer to as the “Severance Plan”. The Severance Plan provides for severance payments and other benefits in the event of a “qualifying termination”, which means a termination of employment by the Company without cause or by the executive officer for “good reason” (as described below) on or within the 12-month period following a change in control of GBT. The Merger will constitute a change in control of GBT for purposes of the Severance Plan. For purposes of the Severance Plan, “good reason” generally means (a) a material diminution in the executive’s job responsibilities (provided that a change in the executive’s

job title or reporting relationship will not be deemed a material diminution in the executive’s job responsibilities); (b) a material diminution in the executive’s then-current base salary; or (c) the Company requiring the executive to be based at an office location which is at least 25 miles from the executive’s then-current office location.

In the event of a qualifying termination, each executive officer would be entitled to receive: (a) a lump-sum cash payment equal to the product of (1) the executive’s applicable multiple (which is 1.5 in the case of Dr. Love and 1.0 in the case of all other executive officers) and (2) the sum of (x) the executive’s annual base salary and (y) the executive’s target annual cash bonus; (b) a pro-rated annual bonus for the portion of the year in which the Effective Time occurs (with the proration based on the executive’s date of termination); (c) subsidized health and welfare benefits premiums for 12 months (or 18 months, in the case of Dr. Love); and (d) outplacement services. Receipt of the above-described payments and benefits is conditioned upon the applicable executive officer executing a release of claims in favor of the Company. The estimated aggregate value of the severance payments and benefits that the Company’s executive officers would receive in the event of a qualifying termination on or following the completion of the Merger is $7,016,851. The foregoing estimate is based on compensation and benefit levels in effect as of August 15, 2022. The executive officers’ outstanding unvested equity awards would be treated as described above in the section entitled “Interests of the Company’s Directors and Executive Officers in the Merger—Treatment of Equity and Equity-Based Awards”.

The Severance Plan provides that in the event that any payment or benefit (regardless of whether payable under the Severance Plan or otherwise and including the acceleration of equity awards) payable to an executive officer in connection with his or her separation from the Company would constitute a parachute payment within the meaning of Section 280G of the Code, then such payment or benefit is only reduced below the limit under Section 280G of the Code if the executive officer would end up in a better financial position than receiving the full amount and paying the 20% excise tax. The Severance Plan does not provide for a gross-up in the event the executive officer is subject to the “golden parachute” excise tax under Section 4999 of the Code.

The Merger Agreement provides that for a period of not less than one year following the Effective Time, Pfizer will, and will cause the Surviving Corporation to, provide each individual who was an employee of the Company or any of its subsidiaries immediately prior to the Effective Time, which we refer to as a “continuing employee”, subject to such individual’s continued employment, with (a) a base salary or base wage and target cash incentive opportunities that are, in each case, no less favorable than such continuing employee’s base salary or base wage and target cash incentive opportunities as in effect immediately prior to the Effective Time, (b) long-term incentive opportunities that are no less favorable than those provided to similarly situated employees of Pfizer, (c) severance benefits that are no less favorable than those provided to such continuing employee immediately prior to the Effective Time and (d) other employee benefits that are substantially comparable in the aggregate to those provided to such continuing employee immediately prior to the Effective Time.

Parent has agreed to, or to cause the Surviving Corporation to, (i) recognize a continuing employee’s service with the Company or any of its subsidiaries prior to the completion of the Merger for all purposes, including determining such continuing employee’s eligibility to participate, level of benefits and vesting, under benefit plans in which continuing employees will participate after the completion of the Merger (subject to certain exceptions), (ii) cause all preexisting condition limitations, exclusions, actively-at-work requirements and waiting periods applicable to continuing employees under the Company’s or the Surviving Corporation’s welfare plans to be waived, to the extent such limitations were waived or satisfied prior to the Effective Time and (iii) provide continuing employees with credit under any such welfare plan for any co-payments or deductibles incurred prior to the Effective Time.

With respect to annual bonuses payable under the Company’s annual bonus plan with respect to fiscal year 2022, if Closing occurs prior to the payment of such bonuses, Pfizer has agreed to pay such bonuses in accordance with the terms of the annual bonus plan and fund the payment pool at no less than the level at which such pool would have been funded assuming achievement of the target level of performance.

Pursuant to the terms of the Merger Agreement, members of the Board and executive officers of the Company will be entitled to certain ongoing indemnification and coverage under directors’ and officers’ liability

insurance policies following the Merger. For a more detailed description of the provisions of the Merger Agreement relating to director and officer indemnification, please see the section of this proxy statement entitled “The Merger Agreement—Indemnification and Insurance”.

In accordance with Item 402(t) of Regulation S-K, the table below sets forth for each of the Company’s named executive officers estimates of the amounts of compensation that are based on or otherwise relate to the Merger and that will or may become payable to the named executive officer either immediately at the Effective Time (i.e., on a “single-trigger” basis) or in the event of a qualifying termination of employment on or following the completion of the Merger (i.e., on a “double-trigger” basis). The holders of shares of GBT common stock are being asked to approve, on a non-binding, advisory basis, such compensation for these named executive officers. Because the vote to approve such compensation is advisory only, it will not be binding on either the Company, the Board or Pfizer. Accordingly, if the proposal to approve the Merger Agreement is approved by the holders of shares of GBT common stock and the Merger is completed, the compensation will be payable regardless of the outcome of the vote to approve such compensation, subject only to the conditions applicable thereto, which are described in the footnotes to the tables below and above under “—Interests of the Company’s Directors and Executive Officers in the Merger”.

The potential payments in the tables below are quantified in accordance with Item 402(t) of Regulation S-K. The estimated values are based on (a) an assumption that the Merger is completed on December 31, 2022, (b) a per share Merger Consideration of $68.50, (c) the named executive officers’ salary and total eligible bonus levels as in effect as of the date of this proxy statement, (d) the number of unvested Company Options, Company RSUs and Company PSUs held by the named executive officers as of August 15, 2022, the latest practicable date to determine such amounts before the filing of this proxy statement, and excluding any additional grants that may occur following such date and any Company Options, Company RSUs and Company PSUs that are vested or are expected to vest in accordance with their terms prior to December 31, 2022, and (e) an assumption that each named executive officer’s employment is terminated by the Company without “cause” or by the named executive officer for “good reason” (each, as defined in the Severance Plan) immediately following the completion of the Merger. In addition, the amounts indicated below are estimates based on multiple assumptions that may or may not actually occur, including assumptions described in this proxy statement, and do not reflect certain compensation actions that may occur before the completion of the Merger. As a result, the actual amounts, if any, to be received by a named executive officer may materially differ from the amounts set forth below.

The amounts shown below do not attempt to quantify any reduction that may be required as a result of a Section 280G best-net cutback; therefore, actual payments to the named executive officers may be less than the amounts indicated below.

As of the date of this proxy statement, there are no employment, equity or other agreements, arrangements or understandings between any of the Company’s directors or executive officers, on the one hand, and Pfizer or the Surviving Corporation, on the other hand, and the Merger is not conditioned upon any of the Company’s directors or executive officers entering into any such agreement, arrangement or understanding.

There is no financing condition to the Merger. Parent and Merger Sub have represented in the Merger Agreement that they have available funds sufficient to consummate the Merger and the other transactions contemplated by the Merger Agreement on the terms contemplated by the Merger Agreement and, at the Effective Time, that Parent and Merger Sub will have available all of the funds necessary for the acquisition of all shares of GBT common stock pursuant to the Merger, as the case may be, to pay all fees and expenses in connection therewith and make payments related to the treatment of GBT equity awards, and to perform their respective obligations under the Merger Agreement.

The closing of the Merger (which we refer to as the “Closing”) will take place at the offices of Cravath, Swaine & Moore LLP, 825 Eighth Avenue, New York, New York 10019, or remotely by exchange of documents and signatures (or their electronic counterparts), at 8:00 a.m., New York City time, on the third business day after the satisfaction or (to the extent permitted by law) waiver of all conditions to Closing, which are described below in the section of this proxy statement entitled “The Merger Agreement—Conditions to the Closing of the Merger” (other than those conditions that by their nature are to be satisfied at the Closing, but subject to the satisfaction or (to the extent permitted by law) waiver by the party or parties entitled to the benefits thereof of those conditions), or at such other place, time and date agreed to in writing by the parties. The date on which the Closing occurs is herein referred to as the “Closing Date”.

The Merger will be accounted for as a “purchase transaction” for financial accounting purposes.

If the Merger is consummated, persons who do not wish to accept the Merger Consideration are entitled to seek appraisal of their shares of GBT common stock under Section 262 and, if all procedures described in Section 262 are strictly complied with, to receive payment in cash for the fair value of their shares of GBT

common stock exclusive of any element of value arising from the accomplishment or expectation of the Merger, as determined by the Delaware Court, together with interest, if any, to be paid upon the amount determined to be the fair value. The “fair value” of your shares of GBT common stock as determined by the Delaware Court may be more or less than, or the same as, the Merger Consideration that you are otherwise entitled to receive under the Merger Agreement. These rights are known as “appraisal rights”. This proxy statement serves as a notice of such appraisal rights pursuant to Section 262.

Persons who exercise appraisal rights under Section 262 will not receive the Merger Consideration they would otherwise be entitled to receive pursuant to the Merger Agreement. They will receive an amount determined to be the “fair value” of their shares of GBT common stock following petition to, and an appraisal by, the Delaware Court. Persons considering seeking appraisal should recognize that the fair value of their shares of GBT common stock determined under Section 262 could be more than, the same as or less than the Merger Consideration they would otherwise be entitled to receive pursuant to the Merger Agreement. Strict compliance with the procedures set forth in Section 262 is required. Failure to comply strictly with all of the procedures set forth in Section 262 may result in the withdrawal, loss or waiver of appraisal rights. Consequently, and in view of the complexity of the provisions of Section 262, persons wishing to exercise appraisal rights are urged to consult their legal and financial advisors before attempting to exercise such rights.

A copy of Section 262 may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262. The following summary is not a complete statement of the law relating to appraisal rights and is qualified in its entirety by reference to Section 262 and any amendments thereto after the date of this proxy statement. Any person who desires to exercise his, her or its appraisal rights should review carefully Section 262 and is urged to consult his, her or its legal advisor before electing or attempting to exercise such rights. The following summary does not constitute legal or other advice, nor does it constitute a recommendation that persons seek to exercise their appraisal rights under Section 262. A person who loses his, her or its appraisal rights will be entitled to receive the Merger Consideration under the Merger Agreement.

A holder of record of shares of GBT common stock and a beneficial owner who (i) continuously holds such shares through the Effective Time, (ii) has not consented to or otherwise voted in favor of the Merger or otherwise withdrawn, lost or waived appraisal rights, (iii) strictly complies with the procedures under Section 262, (iv) does not thereafter withdraw his, her or its demand for appraisal of such shares and (v) in the case of a beneficial owner, a person who (A) reasonably identifies in his, her or its demand the holder of record of the shares for which the demand is made, (B) provides documentary evidence of such beneficial owner’s beneficial ownership and a statement that such documentary evidence is a true and correct copy of what it purports to be and (C) provides an address at which such beneficial owner consents to receive notices given by the Company and to be set forth on the Chancery List (as defined below), will be entitled to receive the fair value of his, her or its shares of GBT common stock exclusive of any element of value arising from the accomplishment or expectation of the Merger, as determined by the Delaware Court, together with interest, if any, to be paid upon the amount determined to be the fair value.

Section 262 requires that where a merger agreement is to be submitted for adoption at a meeting of stockholders, the stockholders be notified that appraisal rights will be available not less than twenty (20) days before the meeting to vote on the merger. Such notice must include either a copy of Section 262 or information directing the stockholders to a publicly available electronic resource at which Section 262 may be accessed without subscription or cost. This proxy statement constitutes the Company’s notice to our stockholders that appraisal rights are available in connection with the Merger, in compliance with the requirements of Section 262. If you wish to consider exercising your appraisal rights, you should carefully review the text of Section 262, which may be accessed without subscription or cost at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262. Failure to comply timely and properly with the requirements of Section 262 will result in the loss of your appraisal rights under the DGCL.

If you elect to demand appraisal of your shares of GBT common stock, you must satisfy each of the following conditions: you must deliver to the Company a written demand for appraisal of your shares of GBT common stock within twenty (20) days after the giving of this notice, which must reasonably inform us of the identity of the holder of record of shares of GBT common stock who intends to demand appraisal of his, her or its shares of GBT common stock and, for beneficial owners only, such demand is accompanied by documentary evidence of such beneficial

owner’s beneficial ownership and a statement that such documentary evidence is a true and correct copy of what it purports to be, and provides an address at which such beneficial owner consents to receive notices given by the Company and to be set forth on the Chancery List; you must not vote or submit a proxy in favor of the proposal to adopt the Merger Agreement; you must hold your shares of GBT common stock continuously through the effective date; and you must comply with the other applicable requirements of Section 262.

A GBT stockholder who elects to exercise appraisal rights must mail or deliver his, her or its written demand for appraisal to the following address or email the demand to the following email address:

A record holder who holds shares of GBT common stock as a nominee for others, such as a broker, fiduciary, depositary or other nominee, may exercise appraisal rights with respect to the shares held for all or less than all beneficial owners of shares as to which such person is the record owner. In such case, the demand must set forth the number of shares of GBT common stock covered by such demand. Where the number of shares of GBT common stock is not expressly stated, the demand will be presumed to cover all shares of GBT common stock outstanding in the name of such record owner.

Within ten (10) days after the Effective Time, the Surviving Corporation must give written notice that the Merger has become effective to each of (a) each GBT stockholder who has properly filed a written demand for appraisal and who did not vote in favor of the proposal to adopt the Merger Agreement and (b) any beneficial owner who has demanded appraisal under Section 262. At any time within sixty (60) days after the Effective Time, any person who has not commenced an appraisal proceeding or joined a proceeding as a named party may withdraw the demand and accept the Merger Consideration specified by the Merger Agreement for that person’s shares of GBT common stock by delivering to the Surviving Corporation a written withdrawal of the demand for appraisal. However, any such attempt to withdraw the demand made more than sixty (60) days after the Effective Time will require written approval of the Surviving Corporation. Unless the demand is properly withdrawn by the person within sixty (60) days after the effective date, no appraisal proceeding in the Delaware Court will be dismissed as to any person without the approval of the Delaware Court, with such approval conditioned upon such terms as the Delaware Court deems just. If the Surviving Corporation does not approve a request to withdraw a demand for appraisal when that approval is required, or if the Delaware Court does not approve the dismissal of an appraisal proceeding, the person will be entitled to receive only the fair value of such person’s shares of GBT common stock determined by the Delaware Court in any such appraisal proceeding, which value could be less than, equal to or more than the Merger Consideration offered pursuant to the Merger Agreement.

Within one hundred twenty (120) days after the Effective Time, but not thereafter, the Surviving Corporation and any person who has properly and timely demanded appraisal and otherwise complied with Section 262 may commence an appraisal proceeding by filing a petition in the Delaware Court, with a copy served on the Surviving Corporation in the case of a petition filed by a person, demanding a determination of the fair value of

the shares of GBT common stock held by all persons that have demanded appraisal. There is no present intent on the part of the Company or the Surviving Corporation to file an appraisal petition and persons seeking to exercise appraisal rights should assume that the Company and the Surviving Corporation will not file such a petition or initiate any negotiations with respect to the fair value of shares of GBT common stock. Accordingly, persons who desire to have their shares of GBT common stock appraised should initiate any petitions necessary for the perfection of their appraisal rights within the time periods and in the manner prescribed in Section 262. If, within one hundred twenty (120) days after the Effective Time, no petition has been filed as provided above, all rights to appraisal will cease and any person that previously demanded appraisal will become entitled only to the Merger Consideration under the Merger Agreement.

In addition, within one hundred twenty (120) days after the Effective Time, any person who has theretofore complied with the applicable provisions of Section 262 will be entitled, upon written request, to receive from the Surviving Corporation a statement setting forth the aggregate number of shares of GBT common stock not consented in writing or otherwise voted in favor of the Merger and with respect to which demands for appraisal were received by the Surviving Corporation and the aggregate number of holders of such shares. Such statement must be mailed within ten (10) days after the written request therefor has been received by the Surviving Corporation or within ten (10) days after the expiration of the period for the delivery of demands as described above, whichever is later.

Upon the filing of a petition by a person, service of a copy of such petition shall be made upon the Surviving Corporation. The Surviving Corporation shall be required to, within twenty (20) days after such service, file in the office of the Register in Chancery in which the petition was filed a duly verified list containing the names and addresses of all persons who have demanded appraisal of their shares of GBT common stock and with whom the Surviving Corporation has not reached agreements as to the value of such shares (which we refer to as the “Chancery List”). The Register in Chancery, if so ordered by the Delaware Court, shall give notice of the time and place fixed for the hearing of such petition by registered or certified mail to the Surviving Corporation and to all such person set forth on the Chancery List.

If a petition for an appraisal is timely filed by a person, at the hearing on such petition, the Delaware Court will determine which persons have complied with Section 262 and have become entitled to appraisal rights provided thereby. The Delaware Court may require the persons who have demanded an appraisal of their shares of GBT common stock and who hold shares represented by certificates to submit their certificates of shares of GBT common stock to the Register in Chancery for notation thereon of the pendency of the appraisal proceedings; and if any person fails to comply with such direction, the Delaware Court may dismiss the proceedings as to such person.

Upon application by the Surviving Corporation or any person entitled to participate in the appraisal proceedings, the Delaware Court may, in its discretion, proceed to trial upon the appraisal prior to the final determination of the persons entitled to appraisal. Any person whose name appears on the Chancery List and may participate fully in all proceedings until it is finally determined that such person is not entitled to appraisal rights under Section 262.

Where proceedings are not dismissed, the appraisal proceeding shall be conducted in accordance with the rules of the Delaware Court, including any rules specifically governing appraisal proceedings. Through such proceedings the Delaware Court shall determine the fair value of shares of GBT common stock taking into account all relevant factors, exclusive of any element of value arising from the accomplishment or expectation of the Merger, together with interest, if any, to be paid upon the amount determined to be the fair value. Unless the Delaware Court, in its discretion, determines otherwise for good cause shown, interest on an appraisal award will accrue and compound quarterly from the Effective Time through the date the judgment is paid at five percent (5%) over the Federal Reserve discount rate (including any surcharge) as established from time to time during the period between the Effective Time and the date of payment of the judgment. At any time before the entry of judgment in the proceedings, the Surviving Corporation may pay to each person entitled to appraisal an amount in cash, in which case interest shall accrue after such payment only on the sum of (x) the difference, if any, between the amount so paid and the fair value of the shares of GBT common stock as determined by the Delaware Court, and (y) interest theretofore accrued, unless paid by the Surviving Corporation as part of the pre-judgment payment to the person.

When the fair value of the shares of GBT common stock is determined, the Delaware Court will direct the payment of such value, with interest thereon, if any, to the persons entitled to receive the same.

Although the Company believes that the Merger Consideration is fair, no representation is made as to the outcome of the appraisal of fair value as determined by the Delaware Court and persons should recognize that such an appraisal could result in a determination of a value higher or lower than, or the same as, the Merger Consideration. Moreover, the Surviving Corporation does not anticipate offering more than the Merger Consideration to any person exercising appraisal rights and reserves the right to assert, in any appraisal proceeding, that, for purposes of Section 262, the “fair value” of the relevant shares of GBT common stock is less than the Merger Consideration.

In determining “fair value”, the Delaware Court is required to take into account all relevant factors. In Weinberger v. UOP, Inc., the Delaware Supreme Court discussed the factors that could be considered in determining fair value in an appraisal proceeding, stating that “proof of value by any techniques or methods which are generally considered acceptable in the financial community and otherwise admissible in court” should be considered and that “[f]air price obviously requires consideration of all relevant factors involving the value of a company.” The Delaware Supreme Court has stated that in making this determination of fair value, the court must consider market value, asset value, dividends, earnings prospects, the nature of the enterprise and any other facts which were known or could be ascertained as of the date of the Merger which throw any light on future prospects of the merged corporation. Section 262 provides that fair value is to be “exclusive of any element of value arising from the accomplishment or expectation of the Merger.” In Cede & Co. v. Technicolor, Inc., the Delaware Supreme Court stated that such exclusion is a “narrow exclusion [that] does not encompass known elements of value,” but which rather applies only to the speculative elements of value arising from such accomplishment or expectation. In Weinberger, the Delaware Supreme Court construed Section 262 to mean that “elements of future value, including the nature of the enterprise, which are known or susceptible of proof as of the date of the Merger and not the product of speculation, may be considered.” In addition, the Delaware courts have decided that the statutory appraisal remedy, depending on factual circumstances, may or may not be a dissenting person’s exclusive remedy.

The cost of the appraisal proceeding may be determined by the Delaware Court and taxed upon the parties as the Delaware Court deems equitable in the circumstances. However, costs do not include attorneys’ and expert witness fees. Each person is responsible for his, her or its attorneys’ and expert witness fees, although, upon application of a person whose name appears on the Chancery List who participated in the proceeding and incurred expenses in connection therewith, the Delaware Court may order that all or a portion of such expenses, including, without limitation, reasonable attorneys’ and expert witness fees, be charged pro rata against the value of all shares of GBT common stock entitled to appraisal not dismissed pursuant to Section 262(k) of the DGCL or subject to such and award pursuant to a reservation of jurisdiction under Section 262(k) of the DGCL. Determinations by the Delaware Court are subject to appellate review by the Delaware Supreme Court.

Any person who has duly demanded appraisal in compliance with Section 262 will not be entitled to vote for any purpose any shares of GBT common stock subject to such demand or to receive payment of dividends or other distributions on such shares, except for dividends or distributions payable to GBT stockholders of record at a date prior to the Effective Time.

At any time within sixty (60) days after the Effective Time, any person who has not commenced an appraisal proceeding or joined such a proceeding as a named party will have the right to withdraw such person’s demand for appraisal and to accept the terms offered in the Merger by delivering to the Surviving Corporation a written withdrawal of the demand for appraisal. No appraisal proceeding in the Delaware Court shall be dismissed as to any person without the approval of the Delaware Court, and such approval may be conditioned upon such terms as the Delaware Court deems just, including without limitation, a reservation of jurisdiction for any application to the Court made under Section 262(j) of the DGCL; provided, however, that this provision shall not affect the right of any person who has not commenced an appraisal proceeding or joined such a proceeding as a named party to withdraw such person’s demand for appraisal and to accept the terms offered upon the Merger within sixty (60) days after the Effective Time. If no petition for appraisal is filed with the Delaware Court within one hundred twenty (120) days after the Effective Time, or if the persons’ otherwise fail to perfect, successfully withdraw or lose such persons’ right to appraisal, all rights to appraisal will cease and any person that previously demanded appraisal will become entitled only to the Merger Consideration under the Merger Agreement.

To the extent there are any inconsistencies between the foregoing summary, on the one hand, and Section 262, on the other hand, Section 262 will govern.

On August 22, 2022, a complaint, captioned Wang v. Global Blood Therapeutics, Inc., et al., Case No. 1:22-cv-07157, was filed in the United States District Court for the Southern District of New York by a purported GBT stockholder, and on August 26, 2022, a complaint, captioned Pepe v. Global Blood Therapeutics, Inc., et al., Case No. 3:22-cv-04895, was filed in the United States District Court for the Northern District of California by a purported GBT stockholder, in each case naming as defendants GBT and members of the Board. The complaints allege, among other things, that the defendants filed or caused to be filed a materially incomplete and misleading preliminary proxy statement with the SEC relating to the Merger in violation of Sections 14(a) and 20(a) of the Exchange Act and Rule 14a-9 promulgated thereunder.

Among other remedies, the complaints seek an order enjoining the defendants from proceeding with the Merger, requiring the defendants to disclose allegedly material information that was allegedly omitted from the proxy statement, rescinding the Merger in the event that it is consummated or granting rescissory damages, awarding costs, including attorneys’ and expert fees and expenses, and granting such other and further relief as the court may deem just and proper.

The defendants believe that the complaints are without merit and that no further disclosure is required to supplement the proxy statement under applicable laws. As of August 26, 2022, GBT was not aware of the filing of other lawsuits challenging the Merger or the proxy statement; however, such lawsuits may be filed in the future.

The following is a general discussion of certain material U.S. federal income tax consequences of the Merger that may be relevant to U.S. Holders and non-U.S. Holders (each, as defined below) of shares of GBT common stock whose shares of GBT common stock are converted into the right to receive cash pursuant to the Merger. This discussion is limited to U.S. Holders and non-U.S. Holders who hold their shares of GBT common stock as “capital assets” within the meaning of Section 1221 of the Internal Revenue Code of 1986, as amended (which we refer to as the “Code”) (generally, property held for investment). This discussion is based upon the Code, Treasury Regulations promulgated under the Code, rulings and other published positions of the Internal Revenue Service (which we refer to as the “IRS”) and judicial decisions, each as in effect on the date of this proxy statement and all of which are subject to change or differing interpretations at any time, possibly with retroactive effect. Any such change or differing interpretation could affect the accuracy of the statements and conclusions set forth in this discussion. No assurance can be given that the IRS would not assert, or that a court would not sustain, a position contrary to any of the tax considerations described in this discussion. No ruling has been or will be sought from the IRS, and no opinion of counsel has or will be rendered, regarding any matter discussed below or the U.S. federal income tax consequences of the Merger.

This discussion is for general information purposes only and does not purport to be a complete analysis of all of the U.S. federal income tax considerations that may be relevant to particular holders in light of their particular facts and circumstances, or to holders subject to special rules under the U.S. federal income tax laws, including, for example:

This discussion of material U.S. federal income tax consequences is not a complete description of all potential U.S. federal income tax consequences of the merger. This discussion does not address any U.S. federal tax considerations other than those pertaining to the income tax (such as the federal estate or gift tax, any alternative minimum tax, or the application of the Medicare tax on net investment income under Section 1411 of the Code) or any state, local or non-U.S. income or non-income tax considerations. In addition, this discussion does not address any considerations in respect of any withholding required pursuant to the Foreign Account Tax Compliance Act of 2010 (including the Treasury Regulations promulgated thereunder and intergovernmental agreements entered into in connection therewith and any laws, regulations or practices adopted in connection with any such agreement). This discussion does not address the tax consequences of any transaction other than the Merger.

If a partnership (including an entity or arrangement treated as a partnership for U.S. federal income tax purposes) is a beneficial owner of shares of GBT common stock, the U.S. federal income tax treatment of a partner in such partnership generally will depend upon the status of the partner, the activities of the partner and the partnership and certain determinations made at the partner level. Accordingly, partners in partnerships holding shares of GBT common stock should consult their tax advisors as to the particular tax consequences to them of the Merger.

THE U.S. FEDERAL INCOME TAX TREATMENT OF THE TRANSACTIONS DISCUSSED HEREIN TO ANY PARTICULAR GBT STOCKHOLDER WILL DEPEND ON THE GBT STOCKHOLDER’S PARTICULAR TAX CIRCUMSTANCES. YOU SHOULD CONSULT YOUR TAX ADVISOR WITH RESPECT TO THE SPECIFIC TAX CONSEQUENCES TO YOU OF THE MERGER IN LIGHT OF YOUR OWN PARTICULAR CIRCUMSTANCES, INCLUDING THE APPLICABILITY AND EFFECT OF ANY U.S. FEDERAL, STATE, LOCAL AND NON-U.S. INCOME, ALTERNATIVE MINIMUM TAX AND OTHER TAX LAWS AND OF CHANGES IN THOSE TAX LAWS.

For purposes of this discussion, a “U.S. Holder” means a beneficial owner of shares of GBT common stock that is for U.S. federal income tax purposes:

A “non-U.S. Holder” means a beneficial owner of GBT common stock that is neither a U.S. Holder nor an entity or arrangement treated as a partnership for U.S. federal income tax purposes.

The receipt of cash by a U.S. Holder in exchange for shares of GBT common stock pursuant to the Merger will be a taxable transaction for U.S. federal income tax purposes. In general, for U.S. federal income tax purposes, a U.S. Holder will recognize gain or loss in an amount equal to the difference, if any, between the amount of cash received pursuant to the Merger and the U.S. Holder’s adjusted tax basis in the shares of GBT common stock surrendered pursuant to the Merger. A U.S. Holder’s adjusted tax basis in its shares of GBT common stock will generally equal the amount that such U.S. Holder paid for such shares. A U.S. Holder’s gain or loss on the disposition of shares of GBT common stock generally will be characterized as capital gain or loss, and any such capital gain or loss generally will be long-term capital gain or loss if such U.S. Holder’s holding period in such shares is more than one year at the time of the Merger. Long-term capital gains of certain non-corporate holders, including individuals, currently are generally subject to U.S. federal income tax at preferential rates. The deductibility of capital losses is subject to limitations. If a U.S. Holder acquired different blocks of GBT common stock at different times or different prices, such U.S. Holder must determine its adjusted tax basis and holding period separately with respect to each block of GBT common stock that it holds.

In general, subject to the discussion below regarding potential backup withholding, the receipt of cash by a non-U.S. Holder in exchange for shares of GBT common stock pursuant to the Merger will not be subject to U.S. federal income tax unless:

Gain described in the first bullet point above generally will be subject to U.S. federal income tax on a net income basis in substantially the same manner as if the non-U.S. Holder were a U.S. Holder (unless an applicable income tax treaty provides otherwise), and if the non-U.S. Holder is a corporation for U.S. federal income tax purposes, it may also be subject to an additional “branch profits tax” at a 30% rate (or such lower rate as may be provided by an applicable income tax treaty) on its “effectively connected earnings and profits” for the taxable year, as adjusted for certain items.

A non-U.S. Holder described in the second bullet point above generally will be subject to U.S. federal income tax at a rate of 30% (or such lower rate as may be provided by an applicable income tax treaty) on any gain recognized, which generally may be offset by U.S.-source capital losses of the non-U.S. Holder recognized in the same taxable year (if any), provided the non-U.S. Holder has timely filed U.S. federal income tax returns with respect to such losses.

With respect to the third bullet point above, GBT believes it has not been, is not and will not be a USRPHC during the five-year period ending on the date of the Effective Time. Even if GBT is or was a USRPHC during the Relevant Period, gain arising from a non-U.S. Holder’s receipt of cash in exchange for shares of GBT common stock pursuant to the Merger will not be subject to U.S. federal income tax if the GBT common stock is “regularly traded”, as defined in applicable Treasury Regulations, on an established securities market, and such non-U.S. Holder owned, actually and constructively, 5% or less of the GBT common stock throughout the Relevant Period.

Generally, information reporting requirements may apply in connection with payments made to U.S. Holders and non-U.S. Holders in connection with the Merger.

Backup withholding of tax (currently, at a rate of 24%) generally will apply to the proceeds received by a U.S. Holder pursuant to the Merger, unless the U.S. Holder provides the applicable withholding agent with a properly completed and executed IRS Form W-9 providing such U.S. Holder’s correct taxpayer identification number and certifying that such U.S. Holder is not subject to backup withholding, or otherwise establishes an exemption, and otherwise complies with the backup withholding rules.

A non-U.S. Holder may be subject to information reporting and backup withholding tax (currently, at a rate of 24%) unless the non-U.S. Holder provides the applicable withholding agent with a properly completed and executed IRS Form W-8BEN or IRS Form W-8BEN-E (or other applicable IRS Form W-8), attesting to such non-U.S. Holder’s status as a non-U.S. person and otherwise complies with applicable certification requirements.

Backup withholding is not an additional tax. The amount of any backup withholding from a payment to a U.S. Holder or a non-U.S. Holder generally will be allowed as a credit against such U.S. Holder’s or non-U.S. Holder’s U.S. federal income tax liability, if any, and may entitle such U.S. Holder or non-U.S. Holder to a refund, provided that the required information is timely furnished to the IRS.

THIS DISCUSSION IS FOR GENERAL INFORMATION PURPOSES ONLY. IT DOES NOT ADDRESS TAX CONSIDERATIONS THAT MAY VARY WITH, OR ARE CONTINGENT ON, YOUR INDIVIDUAL CIRCUMSTANCES OR THE APPLICATION OF ANY U.S. NON-INCOME TAX LAWS OR THE LAWS OF ANY STATE, LOCAL OR NON-U.S. JURISDICTION, AND HOLDERS SHOULD CONSULT THEIR TAX ADVISORS REGARDING SUCH MATTERS AND THE TAX CONSEQUENCES OF THE MERGER TO THEM IN LIGHT OF THEIR PARTICULAR CIRCUMSTANCES, INCLUDING THE APPLICABILITY AND EFFECT OF ANY U.S. FEDERAL, STATE, LOCAL AND NON-U.S. INCOME, ALTERNATIVE MINIMUM TAX AND OTHER TAX LAWS AND OF CHANGES IN THOSE TAX LAWS.

Each of the parties to the Merger Agreement has agreed (subject to the terms and conditions of the Merger Agreement) to cooperate in good faith and use its reasonable best efforts to promptly take, or cause to be taken, all actions, and to do, or cause to be done, and to assist and cooperate with the other parties in doing, all things reasonably necessary, proper or advisable to consummate and make effective the Merger and the other transactions contemplated by the Merger Agreement, including (i) the obtaining of all necessary actions or non-actions, waivers and consents from, the making of all necessary registrations, declarations and filings with any governmental entity with respect to the Merger Agreement or the transactions contemplated thereby and (ii) the defending or contesting of any proceedings challenging the Merger Agreement or the consummation of the transactions contemplated thereby, in each case as described in the section of this proxy statement entitled “The Merger Agreement—Other Covenants—Efforts to Consummate the Merger”. The approvals required under the Merger Agreement include expiry or termination of the waiting period under the HSR Act, as well as the receipt of certain non-U.S. antitrust approvals.

We currently expect to complete the Merger as early as the fourth quarter of 2022. However, we cannot predict the exact timing of completion of the Merger because we cannot guarantee when all required antitrust and other required regulatory approvals will be obtained, or if they will be obtained at all.

Under the HSR Act, the Merger cannot be completed until the waiting period applicable to the Merger has expired or been terminated. A transaction notifiable under the HSR Act may not be completed until the expiration of a 30-day waiting period following the parties’ filings of their HSR Act notification and report forms. If the Federal Trade Commission (which we refer to as the “FTC”) or the Antitrust Division of the Department of Justice (which we refer to as the “DOJ”) issues a request for additional information and documentary materials (which we refer to as a “Second Request”) prior to the expiration of the initial waiting period, the parties must observe a second 30-day waiting period, which would begin to run only after the parties have substantially complied with the Second Request, unless the waiting period is terminated earlier or the parties otherwise agree to extend the waiting period. GBT made the filing required under the HSR Act on August 26, 2022, and we currently expect Parent to make the filing required under the HSR Act by August 29, 2022, in which case the initial 30-day waiting period will be scheduled to expire at 11:59 p.m. Eastern Time on September 28, 2022, unless otherwise extended.

At any time before or after consummation of the Merger, notwithstanding the termination or expiration of the waiting period under the HSR Act, the FTC or the DOJ could take such action under the antitrust laws as it deems necessary or desirable in the public interest, including seeking to enjoin the completion of the Merger, seeking divestiture of substantial assets of the parties, or requiring the parties to license or hold separate assets or terminate existing relationships and contractual rights. At any time before or after the completion of the Merger, any state could take such action under the antitrust laws as it deems necessary or desirable in the public interest. Such action could include seeking to enjoin the completion of the Merger or seeking divestiture of substantial assets of the parties. Private parties may also seek to take legal action under the antitrust laws under certain circumstances. We cannot be certain that a challenge to the Merger will not be made or that, if a challenge is made, we will prevail.

The Merger is also subject to receipt of pending regulatory approval (unless excluded by waiver mutually agreed between the parties) in Germany (pursuant to the Act against Restraints of Competition (Gesetz gegen Wettbewerbsbeschränkungen)). The parties made the required filings with the German Federal Cartel Office (Bundeskartellamt) on August 26, 2022. If, prior to the Effective Time, a merger control inquiry is initiated by a governmental entity in certain specified jurisdictions, the Merger will also be subject to (a) regulatory approval in such jurisdiction or (b) confirmation that the inquiry has ended (unless excluded by waiver mutually agreed between the parties). In each case, the relevant regulatory authorities could take such actions under the applicable regulatory laws as they deem necessary or desirable, including seeking divestiture of substantial assets of the parties or requiring the parties to license, or hold separate, assets or terminate existing relationships and contractual rights. We cannot be certain that a challenge to the Merger will not be made or that, if a challenge is made, we will prevail.

The following summarizes the material provisions of the Merger Agreement. The descriptions of the Merger Agreement in this summary and elsewhere in this proxy statement are not complete and are qualified in their entirety by reference to the Merger Agreement, a copy of which is attached to this proxy statement as Annex A and incorporated into this proxy statement by reference. You should carefully read and consider the entire Merger Agreement, which is the legal document that governs the Merger, because this summary may not contain all of the information about the Merger Agreement that is important to you. The rights and obligations of the parties are governed by the express terms of the Merger Agreement and not by this summary or any other information contained in this proxy statement.

The representations, warranties, covenants and agreements described below and included in the Merger Agreement (a) were made only for purposes of the Merger Agreement and as of specific dates; (b) were made solely for the benefit of the parties to the Merger Agreement; and (c) may be subject to important qualifications, limitations and supplemental information agreed to by GBT, on the one hand, and Parent and Merger Sub, on the other hand, in connection with negotiating the terms of the Merger Agreement. In addition, the representations and warranties have been included in the Merger Agreement for the purpose of allocating contractual risk between GBT, Parent and Merger Sub rather than to establish matters as facts, and may be subject to standards of materiality applicable to such parties that differ from those applicable to investors. GBT stockholders are not third-party beneficiaries under the Merger Agreement and should not rely on the representations, warranties, covenants and agreements or any descriptions thereof as characterizations of the actual state of facts or condition of GBT, Parent or Merger Sub or any of their respective affiliates or businesses. Moreover, information concerning the subject matter of the representations and warranties may change after the date of the Merger Agreement. In addition, you should not rely on the covenants in the Merger Agreement as actual limitations on the respective businesses of GBT, Parent and Merger Sub, because the parties may take certain actions that are either expressly permitted in the confidential disclosure schedules to the Merger Agreement or as otherwise consented to by the appropriate party, which consent may be given without prior notice to the public. The Merger Agreement is described below, and included as Annex A, only to provide you with information regarding its terms and conditions, and not to provide any other factual information regarding GBT, Parent, Merger Sub or their respective businesses. Accordingly, the representations, warranties, covenants and other agreements in the Merger Agreement should not be read alone, and you should read the information provided elsewhere in this document and in our filings with the SEC regarding GBT and our business. For more information, please see the section of this proxy statement entitled “Where You Can Find More Information”.

The Merger Agreement provides that, on the terms and subject to the conditions of the Merger Agreement, and in accordance with the DGCL, at the Effective Time, Merger Sub will merge with and into GBT, the separate corporate existence of Merger Sub will cease and GBT will continue its corporate existence as the Surviving Corporation, becoming a wholly owned subsidiary of Parent. From and after the Effective Time, subject to the terms and conditions of the Merger Agreement and the DGCL, all property, rights, privileges, immunities, powers, franchises, licenses and authority of GBT and Merger Sub will vest in the Surviving Corporation, and all debts, liabilities, obligations, restrictions and duties of each of GBT and Merger Sub will become the debts, liabilities, obligations, restrictions and duties of the Surviving Corporation.

The initial directors of the Surviving Corporation will be the directors of Merger Sub as of the Effective Time, each to hold office until his or her respective successor is duly elected and qualified, or such director’s earlier death, resignation or removal. The initial officers of the Surviving Corporation will be the officers of GBT as of immediately prior to the Effective Time, each to hold office until his or her respective successor is duly elected and qualified, or such officer’s earlier death, resignation or removal.

At the Effective Time, the certificate of incorporation of the Surviving Corporation will be amended and restated to be in the form of the certificate of incorporation attached as Exhibit A to the Merger Agreement and, as so amended and restated, will be the certificate of incorporation of the Surviving Corporation and the bylaws of Merger Sub as in effect immediately prior to the Effective Time will be the bylaws of the Surviving Corporation (except that the name of the Surviving Corporation will be “Global Blood Therapeutics, Inc.”), in each case until as thereafter changed or amended in accordance with applicable law.

The Closing will take place at the offices of Cravath, Swaine & Moore LLP, 825 Eighth Avenue, New York, New York 10019, or remotely by exchange of documents and signatures (or their electronic counterparts), at 8:00 a.m., New York City time, on the third business day after the satisfaction or (to the extent permitted by law) waiver of all conditions to Closing, which are described below in the section of this proxy statement entitled “The Merger Agreement—Conditions to the Closing of the Merger” (other than those conditions that by their nature are to be satisfied at the Closing, but subject to the satisfaction or (to the extent permitted by law) waiver by the party or parties entitled to the benefits thereof of those conditions), or at such other place, time and date agreed to in writing by the parties.

At the Closing, the parties will file a certificate of merger with respect to the Merger with the Secretary of State for the State of Delaware as provided under the DGCL.

At the Effective Time, by virtue of the Merger and without any action on the part of GBT, Parent, Merger Sub or the holders of any securities of GBT or Merger Sub, each share of GBT common stock (other than Excluded GBT Shares) issued and outstanding immediately prior to the Effective Time will be converted automatically into the right to receive the Merger Consideration of $68.50 in cash, without interest and subject to any required tax withholding.

At the Effective Time, subject to all required withholding taxes, equity awards granted on or prior to the date of the Merger Agreement that remain outstanding as of immediately prior to the Effective Time will be treated as follows:

At the Effective Time, equity awards that may be granted to employees of the Company after the date of the Merger Agreement and prior to the Effective Time and that remain outstanding as of immediately prior to the Effective Time will be converted into cash awards (based on the Merger Consideration multiplied by the number of shares of GBT common stock subject to the applicable award immediately prior to the completion of the Merger) subject to the same vesting schedule applicable to the corresponding award.

Prior to the Effective Time, the Board (or, if appropriate, any committee administering the Company Stock Plans) shall adopt such resolutions and take such other actions as may be required to effectuate the actions required by Section 5.04 of the Merger Agreement. All amounts payable pursuant to Section 5.04 of the Merger Agreement shall be subject to any required withholding of Taxes and shall be paid without interest.

As soon as practicable following the Effective Time (but in no event later than five (5) business days following the Effective Time), Parent shall, or shall cause the Surviving Corporation to, pay (through its payroll systems in the case of employees) all amounts payable pursuant to Section 5.04(a) of the Merger Agreement to the former holders of Company Options, Company RSUs and Company PSUs, as applicable; provided, however,

that, to the extent any such amounts relate to a Company Option, Company RSU or Company PSU that constitutes nonqualified deferred compensation subject to Section 409A of the Code, such amounts shall be paid at the earliest time following the Effective Time permitted under the terms of the applicable agreement or Company Stock Plan relating to such Company Option, Company RSU or Company PSU that will not trigger a tax or penalty under Section 409A of the Code.

Prior to the Effective Time, the Company shall take such actions as are necessary (including obtaining any resolutions of the Board or, if appropriate, any committee designated thereby) to provide that (i) no new offering or new purchase period will commence following the date hereof unless and until the Merger Agreement is terminated; (ii) from and after the date hereof, no new participants will be permitted to participate in the Company ESPP and participants will not be permitted to increase their payroll deductions or purchase elections from those in effect on the date of the Merger Agreement; and (iii) the Company ESPP shall terminate effective no later than ten (10) business days prior to the Effective Time. The Company shall determine the rights of participants in the Company ESPP with respect to the offering period underway under the Company ESPP as of the date hereof by treating a business day to be determined by the Company as the last day of such offering period (the “Final Investment Date”), which business day shall be no later than either (x) the date on which such offering period would expire by its terms or (y) the date on which the Company ESPP is terminated, and by treating such shortened offering period as a fully effective and completed offering period for all purposes under the Company ESPP. The Company shall treat any shares of GBT common stock acquired prior to or on the Final Investment Date as outstanding shares of GBT common stock for purposes of Section 2.07(c) of the Merger Agreement.

“Company Stock Plans” means the Company Amended and Restated 2017 Inducement Equity Plan, the Company Amended and Restated 2015 Stock Option and Incentive Plan, the Company 2012 Stock Option and Grant Plan and the Company ESPP.

Prior to the Effective Time, Parent will appoint a bank or trust company reasonably acceptable to the Company to act as paying agent (which we refer to as the “Paying Agent”) to make payments of the Merger Consideration to former GBT stockholders and act as agent for former GBT stockholders for the purpose of receiving and holding their certificates representing shares of GBT common stock (which we refer to as “certificates”) and non-certificated shares of GBT common stock represented by book-entry (which we refer to as “book-entry shares”). On or prior to the Closing Date, Parent will deposit (or cause to be deposited) with the Paying Agent cash necessary to pay the aggregate Merger Consideration in exchange for all shares of GBT common stock outstanding immediately prior to the Effective Time (other than Excluded GBT Shares) (which we refer to as the “Exchange Fund”). The Paying Agent will invest all cash included in the Exchange Fund as directed by Parent, subject to certain limitations set forth in the Merger Agreement and provided that any loss of any of the funds included in the Exchange Fund will not alter Parent’s obligations to pay the Merger Consideration. In the event the Exchange Fund is insufficient to pay the aggregate Merger Consideration for all shares of GBT common stock outstanding immediately prior to the Effective Time (other than Excluded GBT Shares), Parent will promptly deposit (or cause to be deposited) additional funds with the Paying Agent in an amount that is equal to the shortfall required to make such payment.

As soon as reasonably practicable after the Effective Time (and in any event not later than the third business day following the Effective Time), (a) the Paying Agent will mail to each holder of record of a certificate or certificates (other than holders of Excluded GBT Shares) whose shares were converted into the Merger Consideration pursuant to the Merger Agreement (i) a letter of transmittal in such form as is customary and as Parent and GBT may mutually agree and (ii) instructions for effecting the surrender of certificates in exchange for the Merger Consideration and (b) the Paying Agent will mail a check, or make a wire transfer, to each holder of book-entry shares whose shares were converted into the Merger Consideration pursuant to the Merger Agreement. The amount of any Merger Consideration paid to GBT stockholders may be reduced by any applicable withholding taxes.

Upon surrender of certificates or book-entry shares to the Paying Agent together with such letter of transmittal (if required), duly completed and validly executed in accordance with the instructions thereto, and such other documents as may customarily be required by the Paying Agent, the holder of such certificates or book-entry shares (other than holders of Excluded GBT Shares) will be entitled to receive in exchange therefor

an amount in cash equal to the product of (x) the number of shares of GBT common stock formerly represented by such holder’s properly surrendered certificates or book-entry shares multiplied by (y) the Merger Consideration, subject to all required tax withholding. If payment is to be made in respect of any book-entry shares to a Person other than the Person in whose name such book-entry shares are registered, it shall be a condition of payment that the Person requesting such payment shall have paid any transfer or other taxes required by reason of the payment to a Person other than the registered holder of such book-entry shares or shall have established to the satisfaction of Parent and the Paying Agent that such book-entry shares were properly transferred and that such tax either has been paid or is not applicable. In the case of certificates, in the event of a transfer of ownership of GBT common stock that is not registered in the transfer records of the Company, payment may be made to a Person other than the Person in whose name the certificate so surrendered is registered, if such certificate shall be properly endorsed or otherwise be in proper form for transfer and the Person requesting such payment shall have paid any transfer or other taxes required by reason of the payment to a Person other than the registered holder of such Certificate or shall have established to the satisfaction of Parent and the Paying Agent that such tax has been paid or is not applicable.

In the case of any certificate that has been lost, stolen or destroyed, upon the making of an affidavit of that fact by the Person claiming such certificate to be lost, stolen or destroyed and, if required by Parent, the posting by such Person of a bond in customary amount as Parent may direct as indemnity against any claim that may be made against it with respect to such certificate, the Paying Agent will pay in exchange for such lost, stolen or destroyed certificate an amount in cash (after giving effect to any tax withholding as provided in the Merger Agreement and excluding any amounts for interest) equal to (x) the number of shares of GBT common stock formerly represented by such lost, stolen or destroyed certificate multiplied by (y) the Merger Consideration.

Any portion of the Exchange Fund (including the proceeds of any investments thereof) that remains undistributed to GBT stockholders for one year after the Closing Date will be delivered to Parent, upon demand, and any former GBT stockholder who has not surrendered its shares of GBT common stock in accordance with the Merger Agreement will thereafter look only to Parent for payment of their claim for the Merger Consideration, without any interest, upon due surrender of their shares of GBT common stock.

Each of the Paying Agent, Merger Sub, the Company, Surviving Corporation and Parent (and any other applicable withholding agent) is entitled to deduct and withhold from the consideration and any other payments otherwise payable pursuant to the Merger Agreement to any Person such amount as may be required to be deducted and withheld with respect to the making of such payment under any provision of federal, state, local or foreign tax law. Amounts so deducted or withheld and paid over to the appropriate taxing authority will be treated as having been paid to the Person in respect of which such deduction and withholding was made.

The Merger Agreement contains representations and warranties of GBT, Parent and Merger Sub.

Some of the representations and warranties in the Merger Agreement made by GBT are qualified as to “materiality” or “Company Material Adverse Effect”. For purposes of the Merger Agreement, “Company Material Adverse Effect” means any change, event, condition, development, circumstance, effect or occurrence that, individually or in the aggregate, (a) has had, or would reasonably be expected to have, a material adverse effect on the business, assets, financial condition or results of operations of the Company and its subsidiaries, taken as a whole, or (b) would or would reasonably be expected to prevent or impair the consummation of the Merger by the Outside Date, provided that, for purposes of clause (a), none of the following, or any change, event, effect, condition, development, circumstance or occurrence to the extent resulting from or arising in connection with the following, will constitute or be taken into account in determining whether a “Company Material Adverse Effect” has occurred:

In the Merger Agreement, GBT has made customary representations and warranties to Parent and Merger Sub that are subject, in some cases, to specified exceptions and qualifications contained in the Merger Agreement. These representations and warranties relate to, among other things:

In the Merger Agreement, Parent and Merger Sub have made customary representations and warranties to GBT that are subject, in some cases, to specified exceptions and qualifications contained in the Merger Agreement. These representations and warranties relate to, among other things:

The representations and warranties contained in the Merger Agreement will not survive the consummation of the Merger.

Prior to the Effective Time or, if applicable, the date on which the Merger Agreement is earlier terminated in accordance with the Merger Agreement, except (a) as disclosed in the confidential disclosure schedules to the Merger Agreement, (b) as specifically required by the Merger Agreement, (c) as may be required by applicable law or (d) as may be consented to in writing by Parent (which consent shall not be unreasonably withheld, delayed or conditioned), GBT will, and will cause its subsidiaries to:

Prior to the date, if any, on which the Merger Agreement is terminated in accordance with the Merger Agreement, except (a) as disclosed in the confidential disclosure schedules to the Merger Agreement, (b) as specifically required by the Merger Agreement, (c) as may be required by applicable law or (d) as may be consented to in writing by Parent (which consent shall not be unreasonably withheld, delayed or conditioned), GBT will not, and will cause its subsidiaries not to (subject to certain exceptions and thresholds):

Notwithstanding the foregoing, the Company and its subsidiaries may take actions as the Company deems in good faith to be reasonably necessary in connection with COVID-19 or certain COVID-19-related laws, directives or recommendations.

The Company shall not, shall cause the Company Subsidiaries not to, and shall use its reasonable best efforts to cause its and their respective Representatives acting on its or their behalf not to:

The Company shall, and shall cause the Company Subsidiaries and its and their Representatives to, immediately after the execution of the Merger Agreement, (i) cease all solicitations, discussions and negotiations regarding any inquiry, proposal or offer pending on August 7, 2022 that constitutes, or could reasonably be expected to lead to, a Company Takeover Proposal, and (ii) terminate access to any physical or electronic data rooms relating to a possible Company Takeover Proposal.

Notwithstanding the above or any other provision of the Merger Agreement, at any time prior to the receipt of the Company Stockholder Approval:

The Company shall as promptly as reasonably practicable (and in any event within forty-eight (48) hours) advise Parent of (i) any Company Takeover Proposal or (ii) any inquiry or request for discussions, negotiations or non-public information with respect to or that would reasonably be expected to lead to any Company Takeover Proposal. The Company will provide Parent promptly (and in any event within such forty-eight (48)-hour period) with the identity of the Person making any such Company Takeover Proposal, inquiry or request and a correct and complete copy of such Company Takeover Proposal inquiry or request (or, where such Company Takeover Proposal is not in writing, a description of the material terms and conditions of such Company Takeover Proposal, inquiry or request, including any modifications thereto). The Company shall keep Parent reasonably informed of the status (and in any event no later than forty-eight (48) hours after the occurrence of any material changes, developments, discussions or negotiations) of any such Company Takeover Proposal, inquiry or request (including the material terms and conditions thereof and of any modification thereto), and any material developments, discussions and negotiations, including furnishing copies of any written inquiries, correspondence and draft documentation. The Company will not, and will cause each Company Subsidiary not to, enter into any agreement with any Person subsequent to August 7, 2022 that would restrict the

Company’s ability to provide such information to Parent. The Company will promptly provide to Parent any non-public information concerning the Company or any Company Subsidiary provided or made available in accordance with Section 4.02(d) of the Merger Agreement which was not previously provided or made available to Parent.

Neither the Board nor any committee thereof shall: