This Amendment No. 2 (this Amendment) to Schedule
14D-9 amends and supplements the Solicitation/Recommendation Statement on Schedule 14D-9 originally filed by Decibel Therapeutics, Inc., a Delaware corporation
(Decibel), with the U.S. Securities and Exchange Commission (the SEC) on August 25, 2023 (as amended or supplemented from time to time, the Schedule 14D-9), with
respect to the tender offer by Symphony Acquisition Sub, Inc., a Delaware corporation (Purchaser), and a wholly owned subsidiary of Regeneron Pharmaceuticals, Inc., a New York corporation (Regeneron), to acquire all of the
issued and outstanding shares of common stock, of Decibel in exchange for (i) $4.00 per share, payable in cash, without interest and subject to reduction for any applicable withholding of taxes, plus (ii) one contractual, non-tradeable contingent value right per share (each, a CVR), which entitles the holder to potentially receive contingent payments of up to an aggregate of $3.50 per CVR, without interest and subject to
reduction for any applicable withholding taxes, upon the achievement of certain clinical development and regulatory milestones for Decibels lead investigational product candidate, DB-OTO, within
specified time periods and in accordance with the terms and subject to the conditions of a contingent value rights agreement to be entered into with a rights agent mutually agreeable to Regeneron and Decibel, upon the terms and subject to the
conditions set forth in the Offer to Purchase, dated as of August 25, 2023 (together with any amendments or supplements thereto, the Offer to Purchase), and in the related Letter of Transmittal (together with any amendments or
supplements thereto, the Letter of Transmittal, which, together with the Offer to Purchase, constitute the Offer). The Offer is described in a Tender Offer Statement on Schedule TO (as amended or supplemented from time to
time, the Schedule TO) filed jointly by Regeneron and Purchaser with the SEC on August 25, 2023. The Offer to Purchase and the Letter of Transmittal have been filed as Exhibits (a)(1)(A) and (a)(1)(B) to the Schedule 14D-9, respectively.
Capitalized terms used in this Amendment but not defined herein shall have the respective meanings
given to such terms in the Schedule 14D-9. The information set forth in the Schedule 14D-9 remains unchanged and is incorporated herein by reference, except that such
information is hereby amended or supplemented to the extent specifically provided herein.
Explanatory Note:
As previously disclosed, on August 28, 2023, Shoshana Minzer, a purported stockholder of Decibel, filed a complaint in the United States District Court
for the Southern District of New York, captioned Minzer v. Decibel Therapeutics, Inc., et al., 1:23-cv-07626 (S.D.N.Y.) (the Minzer
Complaint). On August 29, 2023, Catherine Coffman, a purported stockholder of Decibel, filed a complaint in the United States District Court for the Southern District of New York, captioned Coffman v. Decibel Therapeutics, Inc.,
et al., 1:23-cv-07668 (S.D.N.Y.) (the Coffman Complaint). Also on August 29, 2023, Ryan ODell, a purported stockholder of Decibel,
filed a complaint in the United States District Court for the Southern District of New York, captioned ODell v. Decibel Therapeutics, Inc., et
al., 1:23-cv-07672 (S.D.N.Y.) (the ODell Complaint). On August 30, 2023, John Clark, a purported stockholder of Decibel, filed a
complaint in the United States District Court for the District of Delaware, captioned Clark v. Decibel Therapeutics, Inc., et
al., 1:23-cv-00946 (D. Del.) (the Clark Complaint). On September 1, 2023, Elaine Wang, a purported stockholder of Decibel, filed a
complaint in the United States District Court for the Southern District of New York, captioned Wang v. Decibel Therapeutics, Inc., et
al., 1:23-cv-07816 (S.D.N.Y.) (the Wang Complaint). On September 6, 2023, Lisa Vorel, a purported stockholder of Decibel, filed a
complaint in the United States District Court for the Southern District of New York, captioned Vorel v. Decibel Therapeutics, Inc., et
al., 1:23-cv-07899 (S.D.N.Y.) (the Vorel Complaint and, collectively with the Minzer Complaint, the Coffman Complaint, the ODell
Complaint, the Clark Complaint, and the Wang Complaint, the Complaints). Decibel has also received correspondence from law firms claiming to represent purported stockholders, demanding that additional disclosures be provided and in some
cases threatening litigation if additional disclosures are not made (the Demands).
Decibel believes that the allegations in the Complaints
and the Demands are without merit, that no supplemental disclosure is required under applicable laws and that the Schedule 14D-9 disclosed all material information required to be disclosed therein. However, to
moot certain of the disclosure claims in the Complaints and the Demands, to avoid the risk that lawsuits may delay or otherwise adversely affect the Transactions and to minimize the expense of defending such actions, Decibel wishes to make
voluntarily certain supplemental disclosures related to the proposed Transactions, all of which are set forth below and should be read in conjunction with the Schedule 14D-9 in its entirety.
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