SYBX · Synlogic, Inc. · Insider Trading

The two transactions reported in Table II above involved the amendment of an outstanding warrant to reduce the exercise price from $3.408 a share to $0.70 a share. The amendment is reported above as the cancellation of the old warrant and the acquisition of a new one.

The warrants were immediately exercisable; provided, however, that the warrants carry a limitation on exercise preventing exercise if such exercise results in New Enterprise Associates 14, L.P. ("NEA 14") beneficially owning in excess of 4.99% (or, at the election of NEA 14, 9.99%) of the number of shares of the Issuer's Common Stock, which percentage can be increased or decreased at the option of NEA 14 upon 61 days' prior notice.

The securities are directly held by NEA 14 and are indirectly held by NEA Partners 14, L.P. ("NEA Partners 14"), the sole general partner of NEA 14, NEA 14 GP, LTD ("NEA 14 LTD"), the sole general partner of NEA Partners 14, and the members of the Executive Committee (the "Executive Committee") of NEA Management Company, LLC (NEA Partners 14, NEA 14 LTD and the members of the Executive Committee together, the "Indirect Reporting Persons"). The members of the Executive Committee are Anthony A. Florence, Jr., Mohamad H. Makhzoumi, and Scott D. Sandell. The Indirect Reporting Persons disclaim beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 14 in which the Indirect Reporting Persons have no pecuniary interest.

The two transactions reported in Table II above involved the amendment of an outstanding warrant to reduce the exercise price from $3.408 a share to $0.70 a share. The amendment is reported above as the cancellation of the old warrant and the acquisition of a new one.

The warrants were immediately exercisable; provided, however, that the warrants carry a limitation on exercise preventing exercise if such exercise results in New Enterprise Associates 14, L.P. ("NEA 14") beneficially owning in excess of 4.99% (or, at the election of NEA 14, 9.99%) of the number of shares of the Issuer's Common Stock, which percentage can be increased or decreased at the option of NEA 14 upon 61 days' prior notice.

The securities are directly held by NEA 14 and are indirectly held by NEA Partners 14, L.P. ("NEA Partners 14"), the sole general partner of NEA 14, NEA 14 GP, LTD ("NEA 14 LTD"), the sole general partner of NEA Partners 14, and the members of the Executive Committee (the "Executive Committee") of NEA Management Company, LLC (NEA Partners 14, NEA 14 LTD and the members of the Executive Committee together, the "Indirect Reporting Persons"). The members of the Executive Committee are Anthony A. Florence, Jr., Mohamad H. Makhzoumi, and Scott D. Sandell. The Indirect Reporting Persons disclaim beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 14 in which the Indirect Reporting Persons have no pecuniary interest.

Represents the number of shares sold by the reporting person on October 29, 2025 to cover the tax liability in connection with the vesting of a restricted stock award, vesting on October 28, 2025, that was granted in 2022.

Per the Amended and Restated Non-Employee Director Compensation Program, amended on April 26, 2025, and the 2015 Equity Incentive Award Plan, the Board of Directors of Synlogic, Inc. awarded each Non-Employee Director 15,000 shares of restricted stock. The shares were granted on April 26, 2025 and will fully vest on December 15, 2025, subject to the Reporting Person continuing to provide services to the Company as a Non-Employee Director, through such vesting date.

Per the Amended and Restated Non-Employee Director Compensation Program, amended on April 26, 2025, and the 2015 Equity Incentive Award Plan, the Board of Directors of Synlogic, Inc. awarded each Non-Employee Director 15,000 shares of restricted stock. The shares were granted on April 26, 2025 and will fully vest on December 15, 2025, subject to the Reporting Person continuing to provide services to the Company as a Non-Employee Director, through such vesting date.

Represents the number of shares sold by the reporting person on April 2, 2025 to cover the tax liability in connection with the vesting of three restricted stock awards, vesting on April 1, 2025, that were granted in 2021, 2022 and 2023.

Represents the number of shares sold by the reporting person on February 3, 2025 to cover the tax liability in connection with the vesting of a restricted stock award, vesting on January 31, 2025, that was granted on January 2, 2024.

Represents the number of shares sold by the reporting person on October 29, 2024 to cover the tax liability in connection with the vesting of a restricted stock award, vesting on October 28, 2024, that was granted on October 28, 2022.

Represents the number of shares sold by the reporting person on April 2, 2024 to cover the tax liability in connection with the vesting of three restricted stock awards, vesting on April 1, 2024, that were granted in 2020, 2021 and 2022.

Represents the number of shares sold by the reporting person on April 2, 2024 to cover the tax liability in connection with the vesting of four restricted stock awards, vesting on April 1, 2024, that were granted in 2020, 2021, 2022 and 2023.

The option vests and becomes exercisable in substantially equal installments on each of the first three anniversaries of the Transaction Date, subject to the Reporting Person continuing to provide services to the Issuer through such vesting date.

The options were issued to the Reporting Person pursuant to the Issuer's Amended and Restated Non-Employee Director Compensation Program and 2015 Equity Incentive Award Plan in lieu of the non-employee director board and committee cash retainers of $81,500 in the aggregate. Such options vest in four equal quarterly installments on the last day of each calendar quarter during 2024 provided the Reporting Person continues to provide services to the Issuer.

The reporting person is a member of Atlas Venture Associates IX, LLC ("AVA IX LLC") and is obligated to transfer the economic benefit, if any, received upon the sale of the shares issuable upon exercise of the equity grants to Atlas Venture Advisors, L.P. As such, the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, except to the extent of his pecuniary interest therein, if any.

The options were issued to the Reporting Person pursuant to the Issuer's Amended and Restated Non-Employee Director Compensation Program and 2015 Equity Incentive Award Plan in lieu of the non-employee director board and committee cash retainers of $48,000 in the aggregate. Such options vest in quarterly installments on the last day of each calendar quarter during 2024 provided the Reporting Person coninues to provide services to the Issuer.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

These performance-based stock options, granted on March 16, 2023, vest when the achievement of certain clinical and regulatory development milestones are met.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2023 through April 1, 2027.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2023 through April 1, 2027.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2021 through April 1, 2025.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2020 through April 1, 2024.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2020 through April 1, 2024.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2021 through April 1, 2025.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2023 through April 1, 2027.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

These performance-based stock options, granted on March 16, 2023, vest when the achievement of certain clinical and regulatory development milestones are met.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on February 4, 2022 through February 4, 2026.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

These stock options vested 25% on the first anniversary of the March 3, 2022 grant date, and vest in 36 substantially-equal monthly installments thereafter, subject to the reporting person's continued employment through the applicable vesting date.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2020 through April 1, 2024.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on July 1, 2020 through July 1, 2024.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on February 4, 2022 through February 4, 2026.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on February 4, 2022 through February 4, 2026.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

These performance-based stock options, granted on March 16, 2023, vest when the achievement of certain clinical and regulatory development milestones are met.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2023 through April 1, 2027.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

These stock options vested 25% on the first anniversary of the March 3, 2022 grant date, and vest in 36 substantially-equal monthly installments thereafter, subject to the reporting person's continued employment through the applicable vesting date.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2020 through April 1, 2024.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on February 4, 2022 through February 4, 2026.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on April 1, 2021 through April 1, 2025.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option vest in approximately equal monthly installments beginning on July 1, 2020 through July 1, 2024.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

These performance-based stock options, granted on March 16, 2023, vest when the achievement of certain clinical and regulatory development milestones are met.

In accordance with the terms of the Synlogic, Inc. 2015 Equity Incentive Award Plan and the Company's 2017 Stock Incentive Plan (together the "Plans"), the Board of Directors of Synlogic, Inc. approved a stock option repricing pursuant to which option awards granted under the Plans were amended to reduce the exercise price to $1.85 per share, the closing stock price of the Company's Common Stock on November 10, 2023. Except for the modified exercise price, all other terms and conditions of each of the option awards will continue as set forth in the Plan and the applicable award agreements.

The shares subject to this option are fully vested as of the date hereof.