Insider Transactions Reported by 16 Insiders of SYNLOGIC, INC.

Symbol: SYBX on OTC
Location: Winchester, MA

Quick Takeaways

SYBX - SYNLOGIC, INC. has 16 insiders with reported activity on this page.
Net insider value flow over the last year: -$284.
Recent transaction rows are available for direct filing-level review.

What Changed

Buy value: ; sell value: $284.
Net share flow: -157.

Why This Matters

This page gives a plain-language issuer insider context before you inspect transaction-level evidence.
Use the filing links below to verify timestamps, codes, and ownership impacts directly from SEC forms.

Source Evidence

Filed on Form 4

Issuer insider activity is sourced from SEC Forms 3, 4, and 5.

See Original Filing

Insider trading overview

Last 12 months

Net insider flow leans to selling over the last 12 months. Net value: -$284.

Buys

Shares: 0

Insiders: 0

Sells

$284

Shares: 157

Insiders: 1

Net

-$284

Shares: -157

Insiders: -1

Window (months)	Sell shares	Buy $	Sell $	Net $
0-3	0	$0	$0	$0
3-6	157	$0	$284	-$284
6-9	0	$0	$0	$0
9-12	0	$0	$0	$0

SYNLOGIC, INC. executives and other stock owners filed with the SEC include:

Name	Relationship	Holdings Value	Past Year Net Change	Change %	Valuation	Report Date
Funicular Funds, LP	10%+ Owner	$1,907,176			Mixed	09 Feb 2024
New Enterprise Associates 14, L.P.	10%+ Owner	$1,682,933			Mixed	03 Oct 2023
Aoife Brennan	President and CEO, Director	$147,578			Filing P/S	10 Nov 2023
Antoine Awad	Chief Operating Officer	$58,576			Filing P/S	02 Apr 2024
Michael Vangsted Jensen	Chief Financial Officer	$27,032			Filing P/S	10 Nov 2023
Mary Beth Dooley	Principal Executive Officer and Principal Financial Officer	$23,066	-$284	-1.2%	Filing P/S	29 Oct 2025
Richard P. Shea	Director	$20,002			Mixed	26 Apr 2025
James P. Flynn	Director	$19,350			Mixed	26 Apr 2025
Mathers Edward T.	Director				Mixed	22 Jun 2023
Gregg Beloff	Interim Chief Financial Officer				Mixed	06 Dec 2021
Michael Thomas Heffernan	Director				Mixed	22 Jun 2023
Lisa Kelly-Croswell	Director				Mixed	22 Jun 2023
Peter Barrett	Director				Mixed	02 Jan 2024
Nick Leschly	Director				Mixed	22 Jun 2023
Patricia N. Hurter	Director				Mixed	02 Jan 2024
Michael F. Burgess	Director				Mixed	22 Jun 2023

Top shareholders of SYNLOGIC, INC. (13F + 13D/G + 3/4/5)

Grouped by holder across the latest SEC ownership disclosures. Ownership % is shown only when it is directly reported or safely comparable across share classes.

Methodology: rows are grouped by holder and ranked by the holder's primary source value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.

Holder	Source	Role / Reporting	Ownership %	Shares	Holdings Value	12M Net Δ	As of	Details
Cable Car Capital, LP	13F	Company	28%	3,312,219	$3,709,685	—	31 Dec 2025	13F
NEA Management Company, LLC	13F	Company	25%	2,922,772	$3,273,505	—	31 Dec 2025	13F
Funicular Funds, LP	13D/G 3/4/5	10%+ Owner	28%	3,312,219	$1,987,331	$0	02 Apr 2026	13D/G 3/4/5
New Enterprise Associates 14, L.P.	3/4/5	10%+ Owner	— class O/S missing	2,922,773	$1,682,933	—	03 Oct 2023	3/4/5
Baselake Partners, LP	13D/G	—	9.7%	1,140,000	$1,265,400	$0	20 Jan 2026	13D/G
Bradley L. Radoff	13D/G	Radoff Bradley Louis	4.4%	520,000	$894,400	$0	30 Sep 2025	13D/G
John A. Kryzanowski	13D/G	Kryzanowski, John A.	6.3%	733,412	$249,360	$0	31 Dec 2024	13D/G
VANGUARD GROUP INC	13F	Company	1.7%	201,060	$225,187	—	31 Dec 2025	13F
CITADEL ADVISORS LLC	13F	Company	1.2%	141,608	$158,601	—	31 Dec 2025	13F
Aoife Brennan	3/4/5	President and CEO, Director	— mixed-class rows	264,967 mixed-class rows	$147,578	—	10 Nov 2023	3/4/5
RENAISSANCE TECHNOLOGIES LLC	13F	Company	0.73%	85,627	$95,902	—	31 Dec 2025	13F
GEODE CAPITAL MANAGEMENT, LLC	13F	Company	0.61%	71,645	$80,247	—	31 Dec 2025	13F
Antoine Awad	3/4/5	Chief Operating Officer	— mixed-class rows	50,525 mixed-class rows	$58,576	—	02 Apr 2024	3/4/5
DRW Securities, LLC	13F	Company	0.21%	24,363	$27,286	—	31 Dec 2025	13F
Michael Vangsted Jensen	3/4/5	Chief Financial Officer	— mixed-class rows	53,613 mixed-class rows	$27,032	—	10 Nov 2023	3/4/5
Mary Beth Dooley	3/4/5	Principal Executive Officer and Principal Financial Officer	0.11%	12,744	$23,066	-$284	29 Oct 2025	3/4/5
Ikarian Capital, LLC	13F	Company	0.17%	19,966	$22,362	—	31 Dec 2025	13F
BlackRock, Inc.	13F	Company	0.17%	19,757	$22,128	—	31 Dec 2025	13F
NORTHERN TRUST CORP	13F	Company	0.17%	19,469	$21,805	—	31 Dec 2025	13F
Richard P. Shea	3/4/5	Director	0.13%	15,506	$20,002	—	26 Apr 2025	3/4/5
James P. Flynn	3/4/5	Director	0.13%	15,000	$19,350	—	26 Apr 2025	3/4/5
JANE STREET GROUP, LLC	13F	Company	0.13%	14,998	$16,797	—	31 Dec 2025	13F
XTX Topco Ltd	13F	Company	0.12%	14,398	$16,126	—	31 Dec 2025	13F
SUSQUEHANNA INTERNATIONAL GROUP, LLP	13F	Company	0.1%	11,623	$13,018	—	31 Dec 2025	13F
STATE STREET CORP	13F	Company	0.09%	10,176	$11,397	—	31 Dec 2025	13F
FMR LLC	13F	Company	0.05%	5,323	$5,962	—	31 Dec 2025	13F
UBS Group AG	13F	Company	0.02%	2,531	$2,835	—	31 Dec 2025	13F
MORGAN STANLEY	13F	Company	0.01%	1,095	$1,226	—	31 Dec 2025	13F
FLAGSHIP HARBOR ADVISORS, LLC	13F	Company	0.01%	1,033	$1,157	—	31 Dec 2025	13F
SBI Securities Co., Ltd.	13F	Company	0%	103	$115	—	31 Dec 2025	13F
BANK OF AMERICA CORP /DE/	13F	Company	0%	66	$73	—	31 Dec 2025	13F
BNP PARIBAS FINANCIAL MARKETS	13F	Company	0%	24	$27	—	31 Dec 2025	13F
Hilltop National Bank	13F	Company	0%	20	$22	—	31 Dec 2025	13F
CITIGROUP INC	13F	Company	0%	1	$1	—	31 Dec 2025	13F
DANSKE BANK A/S	13F	Company	0%	1	$1	—	31 Dec 2025	13F
JPMORGAN CHASE & CO	13F	Company	0%	1	$1	—	31 Dec 2025	13F
Gregg Beloff	3/4/5	Interim Chief Financial Officer	— class O/S missing	50,000	—	—	06 Dec 2021	3/4/5
Lisa Kelly-Croswell	3/4/5	Director	— class O/S missing	30,000	—	—	22 Jun 2023	3/4/5
Mathers Edward T.	3/4/5	Director	— class O/S missing	30,000	—	—	22 Jun 2023	3/4/5
Michael F. Burgess	3/4/5	Director	— class O/S missing	30,000	—	—	22 Jun 2023	3/4/5
Michael Thomas Heffernan	3/4/5	Director	— class O/S missing	30,000	—	—	22 Jun 2023	3/4/5
Nick Leschly	3/4/5	Director	— class O/S missing	30,000	—	—	22 Jun 2023	3/4/5
Peter Barrett	3/4/5	Director	— class O/S missing	24,923	—	—	02 Jan 2024	3/4/5
Patricia N. Hurter	3/4/5	Director	— class O/S missing	14,678	—	—	02 Jan 2024	3/4/5

Recent Insider Transactions by Companies or Individuals for SYNLOGIC, INC.

Showing up to 300 most recent insider transactions from the last 12 months.

Insider	Symbol	Class	Transaction	%	Value $	* Price $	Shares	Shares Owned	Date	Ownership
Mary Beth Dooley	SYBX	Common Stock	Sale	-1.22%	$284	$1.81	-157	12,744	29 Oct 2025	Direct
Richard P. Shea	SYBX	Common Stock	Award	2964.4%			15,000	15,506	26 Apr 2025	Direct
James P. Flynn	SYBX	Common Stock	Award				15,000	15,000	26 Apr 2025	Direct

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