UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULES 13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED

PURSUANT TO RULE 13d-2(b)

(Amendment No. )¹

Synlogic, Inc.

 (Name of Issuer)

Common Stock, par value $0.001 per share

 (Title of Class of Securities)

87166L209

 (CUSIP Number)

April 10, 2024

 (Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐  Rule 13d-1(b)

☒  Rule 13d-1(c)

☐  Rule 13d-1(d)

1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 87166L209

	1	NAME OF REPORTING PERSON
			Bradley L. Radoff
	2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP				(a) ☐
						(b) ☐
	3	SEC USE ONLY
	4	CITIZENSHIP OR PLACE OF ORGANIZATION
			USA
NUMBER OF			5	SOLE VOTING POWER
SHARES
BENEFICIALLY					629,211
OWNED BY			6	SHARED VOTING POWER
EACH
REPORTING					- 0 -
PERSON WITH			7	SOLE DISPOSITIVE POWER
					629,211
			8	SHARED DISPOSITIVE POWER
					- 0 -
	9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
			629,211
	10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES				☐
	11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
			5.4%
	12	TYPE OF REPORTING PERSON
			IN

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CUSIP No. 87166L209

Item 1(a). Name of Issuer:

Synlogic, Inc., a Delaware corporation (the “Issuer”).

Item 1(b). Address of Issuer’s Principal Executive Offices:

301 Binney Street, Suite 402

Cambridge, Massachusetts 02142

Item 2(a). Name of Person Filing:

This statement is filed by Bradley L. Radoff.

Item 2(b). Address of Principal Business Office or, if None, Residence:

The address of the principal office of Mr. Radoff is 2727 Kirby Drive, Unit 29L, Houston, Texas 77098.

Item 2(c). Citizenship:

Mr. Radoff is a citizen of the United States of America.

Item 2(d). Title of Class of Securities:

Common Stock, par value $0.001 per share (the “Shares”).

Item 2(e). CUSIP Number:

87166L209

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CUSIP No. 87166L209

Item 3. If This Statement is Filed Pursuant to Rule 13d-1(b), or 13d-2(b) or (c), Check Whether the Person Filing is a:

	/x/	Not applicable.
(a)	/ /	Broker or dealer registered under Section 15 of the Exchange Act.
(b)	/ /	Bank as defined in Section 3(a)(6) of the Exchange Act.
(c)	/ /	Insurance company as defined in Section 3(a)(19) of the Exchange Act.
(d)	/ /	Investment company registered under Section 8 of the Investment Company Act.
(e)	/ /	An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E).
(f)	/ /	An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F).
(g)	/ /	A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G).
(h)	/ /	A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act.
(i)	/ /	A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act.
(j)	/ /	Non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J).
(k)	/ /	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J), please specify the type of institution: ____

Item 4. Ownership.

(a) Amount beneficially owned:

As of the date hereof, Mr. Radoff directly beneficially owns 629,211 Shares.

(b) Percent of class:

The following percentage is based on 11,646,977 Shares outstanding as of March 12, 2024, which is the total number of Shares outstanding as disclosed in the Issuer’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 19, 2024.

As of the date hereof, Mr. Radoff beneficially owns approximately 5.4% of the outstanding Shares.

(c) Number of shares as to which such person has:

(i) Sole power to vote or to direct the vote:

See Cover Pages Items 5-9.

(ii) Shared power to vote or to direct the vote:

See Cover Pages Items 5-9.

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CUSIP No. 87166L209

(iii) Sole power to dispose or to direct the disposition of:

See Cover Pages Items 5-9.

(iv) Shared power to dispose or to direct the disposition of:

See Cover Pages Items 5-9.

Item 5. Ownership of Five Percent or Less of a Class.

Not Applicable.

Item 6. Ownership of More than Five Percent on Behalf of Another Person.

Not Applicable.

Item 7. Identification and Classification of the Subsidiary That Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable.

Item 8. Identification and Classification of Members of the Group.

Not Applicable.

Item 9. Notice of Dissolution of Group.

Not Applicable.

Item 10. Certifications.

By signing below the undersigned certifies that, to the best of his knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

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CUSIP No. 87166L209

SIGNATURE

After reasonable inquiry and to the best of his knowledge and belief, the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: April 18, 2024

/s/ Bradley L. Radoff

Bradley L. Radoff

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