Mary Beth Dooley - 29 Oct 2025 Form 4 Insider Report for SYNLOGIC, INC. (SYBX)

Role: Principal Executive Officer and Principal Financial Officer
Signature: /s/ Mary Beth Dooley
Issuer symbol: SYBX
Transactions as of: 29 Oct 2025
Net transactions value: -$284
Form type: 4
Filing time: 31 Oct 2025, 15:30:03 UTC
Previous filing: 03 Apr 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Dooley Mary Beth	Principal Executive Officer and Principal Financial Officer	C/O SYNLOGIC, INC., PO BOX 30, WINCHESTER	/s/ Mary Beth Dooley	31 Oct 2025	0002015112

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	SYBX	Common Stock	Sale	$284	-157	-1.2%	$1.81	12,744	29 Oct 2025	Direct	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	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.

Remarks:

Principal Executive Officer and Principal Financial Officer