COGT · Cogent Biosciences, Inc.

The option award was issued to the Reporting Person, who elected to take shares in lieu of cash compensation for services as a director, pursuant to the Issuer's non-employee director compensation plan. The number of options granted was determined by dividing the cash compensation otherwise payable with respect to the quarter by the Black-Scholes value of a single option calculated as of the date of the grant.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2027 Annual Meeting of Stockholders, subject to the Reporting Person's continued service to the Issuer through such date.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2027 Annual Meeting of Stockholders, subject to the Reporting Person's continued service to the Issuer through such date.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2027 Annual Meeting of Stockholders, subject to the Reporting Person's continued service to the Issuer through such date.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2027 Annual Meeting of Stockholders, subject to the Reporting Person's continued service to the Issuer through such date.

Under the Reporting Person's arrangement with Fairmount Funds Management LLC (the "Adviser"), the Reporting Person holds the option for one or more investment vehicles managed by the Adviser (each, a "Fairmount Fund"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received from the option for the benefit of such Fairmount Fund. The Reporting Person therefore disclaims beneficial ownership of the option and underlying common stock.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2027 Annual Meeting of Stockholders, subject to the Reporting Person's continued service to the Issuer through such date.

Under the Reporting Person's arrangement with Fairmount Funds Management LLC (the "Adviser"), the Reporting Person holds the option for one or more investment vehicles managed by the Adviser (each, a "Fairmount Fund"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received from the option for the benefit of such Fairmount Fund. The Reporting Person therefore disclaims beneficial ownership of the option and underlying common stock.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2027 Annual Meeting of Stockholders, subject to the Reporting Person's continued service to the Issuer through such date.

On May 19, 2026, Mr. Robbins transferred 160,000 shares of common stock to a family trust for estate planning purposes.

On May 19, 2026, Mr. Robbins transferred 160,000 shares of common stock to a family trust for estate planning purposes.

The option award was issued to the Reporting Person, who elected to take shares in lieu of cash compensation for services as a director, pursuant to the Issuer's non-employee director compensation plan. The number of options granted was determined by dividing the cash compensation otherwise payable with respect to the quarter by the Black-Scholes value of a single option calculated as of the date of the grant.

Each share of Series A Convertible Preferred Stock is convertible into shares of Common Stock at any time at the option of the holder thereof, into 250 shares of Common Stock, subject to certain limitations, including that a holder of Series A Preferred Stock is prohibited from converting shares of Series A Preferred Stock into shares of Common Stock if, as a result of such conversion, such holder, together with its affiliates, would beneficially own more than 9.9% of the total number of shares of Common Stock issued and outstanding immediately after giving effect to such conversion. On March 31, 2026, the Reporting Persons converted 28,000 shares of Series A Convertible Preferred Stock into 7,000,000 shares of Common Stock for no cash consideration, in accordance with the Certificate of Designations for the Series A Convertible Preferred Stock.

Fairmount Funds Management LLC and Fairmount Healthcare Fund II GP LLC have voting power and investment power over the securities held by Fairmount Healthcare Fund II LP ("Fund II"). They disclaim beneficial ownership of securities held by Fund II for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

Each share of Series A Convertible Preferred Stock is convertible into shares of Common Stock at any time at the option of the holder thereof, into 250 shares of Common Stock, subject to certain limitations, including that a holder of Series A Preferred Stock is prohibited from converting shares of Series A Preferred Stock into shares of Common Stock if, as a result of such conversion, such holder, together with its affiliates, would beneficially own more than 9.9% of the total number of shares of Common Stock issued and outstanding immediately after giving effect to such conversion. On March 31, 2026, the Reporting Persons converted 28,000 shares of Series A Convertible Preferred Stock into 7,000,000 shares of Common Stock for no cash consideration, in accordance with the Certificate of Designations for the Series A Convertible Preferred Stock.

Fairmount Funds Management LLC and Fairmount Healthcare Fund II GP LLC have voting power and investment power over the securities held by Fairmount Healthcare Fund II LP ("Fund II"). They disclaim beneficial ownership of securities held by Fund II for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

Fairmount Funds Management LLC and Fairmount Healthcare Fund II GP LLC have voting power and investment power over the securities held by Fairmount Healthcare Fund II LP ("Fund II"). They disclaim beneficial ownership of securities held by Fund II for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

Fairmount Funds Management LLC and Fairmount Healthcare Fund II GP LLC have voting power and investment power over the securities held by Fairmount Healthcare Fund II LP ("Fund II"). They disclaim beneficial ownership of securities held by Fund II for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

The option award was issued to the Reporting Person, who elected to take shares in lieu of cash compensation for services as a director, pursuant to the Issuer's non-employee director compensation plan. The number of options granted was determined by dividing the cash compensation otherwise payable with respect to the quarter by the Black-Scholes value of a single option calculated as of the date of the grant.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $38.52 to $38.94, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

Includes previously reported shares of common stock underlying restricted stock units granted to the Reporting Person, which are subject to certain vesting conditions.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $38.53 to $38.88, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

Includes previously reported shares of common stock underlying restricted stock units granted to the Reporting Person, which are subject to certain vesting conditions.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $38.51 to $39.01, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

Includes previously reported shares of common stock underlying restricted stock units granted to the Reporting Person, which are subject to certain vesting conditions.

The price reported above is a weighted average price. The shares were sold in multiple transactions at prices ranging from $38.51 to $38.94, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

Includes previously reported shares of common stock underlying restricted stock units granted to the Reporting Person, which are subject to certain vesting conditions.

Represents acquisition of shares of common stock in connection with the vesting of a performance-based RSU award granted in February 2023 (the "2023 PSUs").

Represents acquisition of shares of common stock in connection with the vesting of a performance-based RSU award granted in February 2023 (the "2023 PSUs").

This stock option shall vest in equal monthly installments over a four year period, subject to the Reporting Person's continuing service to the Issuer through such dates.

Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings in connection with the vesting of the 2023 PSUs.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings in connection with the vesting of the 2023 PSUs.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

This stock option shall vest in equal monthly installments over a four year period, subject to the Reporting Person's continuing service to the Issuer through such dates.

Represents acquisition of shares of common stock in connection with the vesting of a performance-based RSU award granted in February 2023 (the "2023 PSUs").

This stock option shall vest in equal monthly installments over a four year period, subject to the Reporting Person's continuing service to the Issuer through such dates.

This stock option shall vest in equal monthly installments over a four year period, subject to the Reporting Person's continuing service to the Issuer through such dates.

This stock option shall vest in equal monthly installments over a four year period, subject to the Reporting Person's continuing service to the Issuer through such dates.

Award of Restricted Stock Units ("RSUs") under the Issuer's 2018 Stock Option and Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date, subject to the Reporting Person's continuing service with the Issuer through such dates.

Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings in connection with the vesting of the 2023 PSUs.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Represents acquisition of shares of common stock in connection with the vesting of a performance-based RSU award granted in February 2023 (the "2023 PSUs").

Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings in connection with the vesting of the 2023 PSUs.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Represents acquisition of shares of common stock in connection with the vesting of a performance-based RSU award granted in February 2023 (the "2023 PSUs").

Award of Restricted Stock Units ("RSUs") under the Issuer's 2018 Stock Option and Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date, subject to the Reporting Person's continuing service with the Issuer through such dates.

This stock option shall vest in equal monthly installments over a four year period, subject to the Reporting Person's continuing service to the Issuer through such dates.

Award of Restricted Stock Units ("RSUs") under the Issuer's 2018 Stock Option and Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date, subject to the Reporting Person's continuing service with the Issuer through such dates.

Represents acquisition of shares of common stock in connection with the vesting of a performance-based RSU award granted in February 2023 (the "2023 PSUs").

Award of Restricted Stock Units ("RSUs") under the Issuer's 2018 Stock Option and Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date, subject to the Reporting Person's continuing service with the Issuer through such dates.

Includes an aggregate of 1,602 shares of common stock acquired by the Reporting Person under the Issuer's 2018 Employee Stock Purchase Plan on June 30, 2025.

Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings in connection with the vesting of the 2023 PSUs.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Award of Restricted Stock Units ("RSUs") under the Issuer's 2018 Stock Option and Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date, subject to the Reporting Person's continuing service with the Issuer through such dates.

Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings in connection with the vesting of the 2023 PSUs.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Award of Restricted Stock Units ("RSUs") under the Issuer's 2018 Stock Option and Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date, subject to the Reporting Person's continuing service with the Issuer through such dates.

The option award was issued to the Reporting Person, who elected to take shares in lieu of cash compensation for services as a director, pursuant to the Issuer's non-employee director compensation plan. The number of options granted was determined by dividing the cash compensation otherwise payable with respect to the quarter by the Black-Scholes value of a single option calculated as of the date of the grant.

Fairmount Funds Management LLC and Fairmount Healthcare Fund II GP LLC have voting power and investment power over the securities held by Fairmount Healthcare Fund II LP ("Fund II"). They disclaim beneficial ownership of securities held by Fund II for purposes of Rule 16a-1(a)(2), except to the extent of their pecuniary interest therein.

The option award was issued to the Reporting Person, who elected to take shares in lieu of cash compensation for services as a director, pursuant to the Issuer's non-employee director compensation plan. The number of options granted was determined by dividing the cash compensation otherwise payable with respect to the quarter by the Black-Scholes value of a single option calculated as of the date of the grant.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2026 Annual Meeting of Stockholders.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2026 Annual Meeting of Stockholders.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2026 Annual Meeting of Stockholders.

Under the Reporting Person's arrangement with Fairmount Funds Management LLC (the "Adviser"), the Reporting Person holds the option for one or more investment vehicles managed by the Adviser (each, a "Fairmount Fund"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received from the option for the benefit of such Fairmount Fund. The Reporting Person therefore disclaims beneficial ownership of the option and underlying common stock.

This stock option shall vest in full upon the earlier of the first anniversary of the date of grant or the date of the 2026 Annual Meeting of Stockholders.

Under the Reporting Person's arrangement with Fairmount Funds Management LLC (the "Adviser"), the Reporting Person holds the option for one or more investment vehicles managed by the Adviser (each, a "Fairmount Fund"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received from the option for the benefit of such Fairmount Fund. The Reporting Person therefore disclaims beneficial ownership of the option and underlying common stock.