SYNLOGIC, INC. — Director's Dealing 2017

Aug 30, 2017

SEC Form 3 — Initial Statement of Beneficial Ownership

Issuer: SYNLOGIC, INC. (SYBX)
CIK: 0001527599
Period of Report: 2017-08-28

Reporting Person: Brennan Aoife (Chief Medical Officer)

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	51767	Direct

Holdings (Derivative)

Security	Exercise Price	Expiration	Underlying	Shares	Ownership
Stock Option (right to buy)	$13.53	2027-05-15	Common Stock (42413)		Direct
Stock Option (right to buy)	$13.53	2027-05-15	Common Stock (41490)		Direct

Footnotes

F1: Shares of capital stock of the corporation then known as Synlogic, Inc. ("Old Synlogic") were converted into shares of the Issuer pursuant to that certain Agreement and Plan of Merger and Reorganization, dated as of May 15, 2017, by and among the Issuer, Meerkat Merger Sub, Inc. and Old Synlogic (the "Merger Agreement"). Pursuant to the terms of the Merger Agreement, each share of capital stock was exchanged for 0.5532 shares of the Issuer's common stock, giving effect to a reverse split of the Issuer's common stock of 7-to-1.

F2: On May 15, 2017, Reporting Person was granted 93,578 shares of common stock of Old Synlogic subject to a restricted stock agreement, dated May 15, 2017, by and between Old Synlogic and the Reporting Person, under the 2017 Stock Plan (the "2017 Plan"). Pursuant to the Merger Agreement, this common stock was converted into 51,767 shares of the Issuer's common stock. One-fourth of the total number of shares subject to the restricted stock agreement vest on September 1, 2017 and the remainder vest in equal monthly installments until September 1, 2020, provided that at the relevant vesting dates the Reporting Person continues service to the Issuer and has not been terminated as defined in and as determined under the 2017 Plan.

F3: On May 15, 2017, Reporting Person was granted an option to purchase 76,669 shares of common stock of Old Synlogic under the 2017 Plan at an exercise price of $7.48 per share. Pursuant to the Merger Agreement, this option was converted into an option to purchase 42,413 shares of the Issuer's common stock at a per share exercise price of $13.53. One fourth of the total number of shares subject to the option vest on September 1, 2017 and the remainder vest in equal monthly installments until September 1, 2020, provided that at the relevant vesting dates the Reporting Person continues service to the Issuer and has not been terminated as defined in and as determined under the Plan. The option expires ten years after the date of the grant.

F4: On May 15, 2017, Reporting Person was granted an option to purchase 75,000 shares of common stock of Old Synlogic under the 2017 Plan at an exercise price of $7.48 per share. Pursuant to the Merger Agreement, this option was converted into an option to purchase 41,490 shares of the Issuer's common stock at a per share exercise price of $13.53. The shares vest in equal monthly installments beginning on June 15, 2017 and continuing until May 15, 2021, provided that at the relevant vesting dates the Reporting Person continues service to the Issuer and has not been terminated as defined in and as determined under the Plan. The option expires ten years after the date of the grant.