SEC FORM 4

SEC FORM 4 SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Brennan Aoife

(Last)

(First)

(Middle)

C/O SYNLOGIC, INC.

301 BINNEY STREET, SUITE 402

(Street)

CAMBRIDGE

02142

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
SYNLOGIC, INC. [ SYBX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director	10% Owner
X	Officer (give title below)	Other (specify below)
President and CEO

3. Date of Earliest Transaction (Month/Day/Year)
11/10/2023

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (right to buy)	$202.95⁽¹⁾	11/10/2023		D			5,591	⁽²⁾	05/15/2027	Common Stock	5,591	⁽¹⁾	0	D
Stock Option (right to buy)	$149.25⁽¹⁾	11/10/2023		D			3,733	⁽²⁾	03/14/2028	Common Stock	3,733	⁽¹⁾	0	D
Stock Option (right to buy)	$143.25⁽¹⁾	11/10/2023		D			3,600	⁽²⁾	06/05/2028	Common Stock	3,600	⁽¹⁾	0	D
Stock Option (right to buy)	$118.65⁽¹⁾	11/10/2023		D			9,999	⁽²⁾	10/31/2028	Common Stock	9,999	⁽¹⁾	0	D
Stock Option (right to buy)	$128.85⁽¹⁾	11/10/2023		D			12,332	⁽²⁾	03/05/2029	Common Stock	12,332	⁽¹⁾	0	D
Stock Option (right to buy)	$25.5⁽¹⁾	11/10/2023		D			12,352	⁽³⁾	03/10/2030	Common Stock	12,352	⁽¹⁾	0	D
Stock Option (right to buy)	$52.5⁽¹⁾	11/10/2023		D			18,999	⁽⁴⁾	03/10/2031	Common Stock	18,999	⁽¹⁾	0	D
Stock Option (right to buy)	$29.25⁽¹⁾	11/10/2023		D			28,943	⁽⁵⁾	02/04/2032	Common Stock	28,943	⁽¹⁾	0	D
Stock Option (right to buy)	$9.3⁽¹⁾	11/10/2023		D			42,999	⁽⁶⁾	03/16/2033	Common Stock	42,999	⁽¹⁾	0	D
Stock Option (right to buy)	$9.3⁽¹⁾	11/10/2023		D			8,666	⁽⁷⁾	03/16/2033	Common Stock	8,666	⁽¹⁾	0	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		5,591		⁽²⁾	05/15/2027	Common Stock	5,591	⁽¹⁾	5,591	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		3,733		⁽²⁾	03/14/2028	Common Stock	3,733	⁽¹⁾	3,733	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		3,600		⁽²⁾	06/05/2028	Common Stock	3,600	⁽¹⁾	3,600	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		9,999		⁽²⁾	10/31/2028	Common Stock	9,999	⁽¹⁾	9,999	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		12,332		⁽²⁾	03/05/2029	Common Stock	12,332	⁽¹⁾	12,332	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		12,352		⁽³⁾	03/10/2030	Common Stock	12,352	⁽¹⁾	12,352	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		18,999		⁽⁴⁾	03/10/2031	Common Stock	18,999	⁽¹⁾	18,999	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		28,943		⁽⁵⁾	02/04/2032	Common Stock	28,943	⁽¹⁾	28,943	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		42,999		⁽⁶⁾	03/16/2033	Common Stock	42,999	⁽¹⁾	42,999	D
Stock Option (right to buy)	$1.85⁽¹⁾	11/10/2023		A		8,666		⁽⁷⁾	03/16/2033	Common Stock	8,666	⁽¹⁾	8,666	D

Explanation of Responses:

1. 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.

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

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

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

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

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

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

	/s/ Aoife Brennan	11/14/2023
	** Signature of Reporting Person	Date
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SEC Form 4 filed by Brennan Aoife