6. Stock-Based Compensation

2018 Stock Option and Incentive Plan

The Company’s 2018 Stock Option and Incentive Plan, (the “2018 Plan”), which became effective on March 27, 2018, provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards, cash-based awards and dividend equivalent rights. The number of shares initially reserved for issuance under the 2018 Plan was 700,180. Additionally, the shares of common stock that remained available for issuance under the previously outstanding 2015 Stock Incentive Plan (the “2015 Plan”) became available under the 2018 Plan. The number of shares reserved for the 2018 Plan automatically increases on each January 1 by 4% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or a lesser number of shares determined by the Company’s board of directors. At the Company’s 2021 annual stockholder meeting, the Company’s stockholders approved the amendment and restatement of the 2018 Plan to increase the number of shares of common stock issuable under the 2018 Plan by 6,000,000 shares. At the Company’s 2023 annual stockholder meeting, the Company’s stockholders approved the amendment and restatement of the 2018 Plan to increase the number of shares of common stock issuable under the 2018 Plan by an additional 6,000,000 shares.

The shares of common stock underlying any awards that are forfeited, canceled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, repurchased or are otherwise terminated by the Company under the 2018 Plan or the 2015 Plan will be added back to the shares of common stock available for issuance under the 2018 Plan.

The number of authorized shares reserved for issuance under the 2018 Plan was increased by 6,439,201 shares effective as of January 1, 2026. As of June 30, 2026, 1,999,348 shares of common stock remain available for issuance under the 2018 Plan.

Inducement Plan

On October 22, 2020, the board of directors adopted the Cogent Biosciences, Inc. 2020 Inducement Plan (the “Inducement Plan”). A total of 3,750,000 shares of common stock were initially reserved for issuance under the Inducement Plan, and, as of June 30, 2026, an additional 2,800,000 shares of common stock have been reserved for issuance under the Inducement Plan. As of June 30, 2026, 1,016,303 shares of common stock remain available for issuance under the Inducement Plan.

2018 Employee Stock Purchase Plan

The Company’s 2018 Employee Stock Purchase Plan (the “ESPP”) became effective on March 28, 2018, at which time a total of 78,500 shares of common stock were reserved for issuance. The number of shares of common stock that may be issued under the ESPP automatically increases on each January 1 through January 1, 2027, by the least of (i) 125,000 shares of common stock, (ii) 1% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or (iii) such lesser number of shares as determined by the ESPP administrator. The number of authorized shares reserved for issuance under the ESPP was increased by 125,000 shares effective as of January 1, 2026. As of June 30, 2026, 254,605 shares remain available for issuance under the ESPP.

Performance-based restricted stock units

In 2023 and 2024, the Board of Directors approved grants to executives in aggregate of up to 2,714,000 performance-based restricted stock units (“PSUs”) under the 2018 Plan that were eligible to vest over a performance period ending in February 2026 (“2023 Executive PSUs”). An award holder could generally receive between 0% and 200% of the target award based on achievement of specified stock price hurdles and/or research and development milestones at any time during the performance period. Any 2023 Executive PSUs earned during the performance period would vest, if at all, in a single tranche in February 2026 subject to a condition of continuing employment through the end of the performance period. The fair value of the market-based awards was estimated on the date of grant for accounting purposes using a Monte Carlo simulation model. The fair value of the performance-based awards was based on the closing share price of the Company’s common stock on the accounting grant date. In December 2025, the Board of Directors determined that the 2023 Executive PSUs had been achieved at the maximum level and approved the acceleration of vesting of all such PSUs and the Company recognized the remaining expense of $1.1 million in the fourth quarter of 2025.

In October 2025, the Board of Directors approved grants to executives in aggregate of up to 3,650,000 PSUs under the 2018 Plan that were eligible to vest over a performance period ending in December 2028 (“2025 Executive PSUs”). An award holder could generally receive between 0% and 200% of the target award based on achievement of specified stock price hurdles or development and commercial milestones at any time during the performance period. Any 2025 Executive PSUs earned during the performance period will vest, if at all, in a single tranche in December 2028 subject to a condition of continuing employment through the end of the performance period. The fair value of the market-based awards was estimated on the date of grant for accounting purposes using a Monte Carlo simulation model. The fair value of the performance-based awards was based on the closing share price of the Company’s common stock on the accounting grant date. In the fourth quarter of 2025, the maximum number of awards was deemed earned as a result of the achievement of the maximum stock price target.

During the year ended December 31, 2025, the Company granted 340,000 PSUs to certain non-executives (“Non-executive PSUs”) under the 2018 Plan. These awards were subject to the holders’ continuous service to the Company through the vesting event. In May 2026, the awards vested as a result of the achievement of performance milestones and the Company recognized the remaining expense of $0.8 million in the second quarter of 2026.

Stock-Based Compensation

As of June 30, 2026, total unrecognized compensation cost related to the unvested stock options and restricted stock units was $94.6 million and $44.0 million, respectively, which is expected to be recognized over a weighted average period of 2.4 years and 3.6 years, respectively.

As of June 30, 2026, the total amount of unrecognized compensation cost related to unvested PSUs, all of which relate to the 2025 Executive PSUs, where the market or performance criteria have been achieved or are probable of achievement was $29.9 million, which is expected to be recognized over a weighted average period of 2.5 years.