In May 2022, the Company’s Board of Directors adopted, and in June 2022, the Company’s stockholders approved, the MaxCyte, Inc. 2022 Equity Incentive Plan (the “2022 Plan”) to provide for the awarding of (i) incentive stock options, (ii) non-qualified stock options, (iii) stock appreciation rights, (iv) restricted stock awards, (v) restricted stock unit awards, (vi) performance awards, and (vii) other awards. Following the approval of the 2022 Plan, no additional awards can be granted under the 2016 Plan or the Inducement Plan, but all outstanding awards will continue to remain subject to the terms of the applicable plan.
Upon the effectiveness of the 2022 Plan, a total of 3,692,397 shares were initially reserved for issuance pursuant to future awards under the 2022 Plan, consisting of 1,928,000 new shares and 1,764,397 shares previously available under the 2016 Plan. If and to the extent that outstanding options under the 2016 Plan or the Inducement Plan are forfeited, the shares underlying such forfeited options will become available for issuance under the 2022 Plan. At the Company’s Annual Meeting of Stockholders held on June 22, 2023, the Company’s stockholders voted to reserve an additional 6,069,000 shares of issuance pursuant to future awards under the 2022 Plan. At the Company’s Annual Meeting of Stockholders held on June 11, 2024, the Company’s stockholders approved to increase by 2,300,000 the maximum number of shares of common stock authorized to be issued under the 2022 Plan.
At June 30, 2024 and December 31, 2023, there were 6,802,000 and 6,202,000 shares, respectively, available to be issued under the 2022 Plan.
The value of an equity award is recognized as expense on a straight-line basis over the requisite service period. At June 30, 2024, total unrecognized compensation expense was $23,617, which will be recognized over an estimated weighted average period of 2.4 years.
Stock Options
The weighted-average fair value of the stock options granted during the three months ended June 30, 2024 and 2023 was estimated to be $2.45 and $2.09, per option share, respectively. The weighted-average fair value of the stock options granted during the six months ended June 30, 2024 and 2023 was estimated to be $2.28 and $2.05, per option share, respectively.
Restricted Stock Units (“RSUs”)
The weighted-average fair value of the RSUs granted during the three months ended June 30, 2024 and 2023 was estimated to be $4.69 and $3.73 per RSU, respectively. The weighted-average fair value of the RSUs granted during the six months ended June 30, 2024 and 2023 was estimated to be $4.43 and $4.30 per RSU, respectively.
Performance Stock Units (“PSUs”)
During the six months ended June 30, 2024, 550,838 PSUs were awarded to certain members of management and executive officers. The PSU awards represent a number of shares of common stock to be earned if a target level of performance, as approved by the Board of Directors, is achieved. The performance period continues through December 31, 2026. The actual number of shares of common stock underlying the PSUs to be earned will be between 0% and 125% of the target number of PSUs, depending on the level of achievement of such performance metrics. The weighted-average fair value of the PSUs granted during the three and six months ended June 30, 2024 was estimated to be $4.31 per PSU. During the three months ended June 30, 2024, the Company determined that it was probable that the grants will vest at 100% of the target number of PSUs. Stock-based compensation expense for the service period since the grant date of $197 and $395 was recognized in the three and six months ended June 30, 2024, respectively. The Company did not issue PSUs prior to January 2024.
Employee Stock Purchase Plan (“ESPP”)
In May 2023, the Company commenced the initial offering under the ESPP. The ESPP provides an offering period of 24 months, with four purchase periods that are generally six months long (each, a “Purchase Period”). The third Purchase