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

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * Pomerantz Roger   2. Issuer Name and Ticker or Trading Symbol Seres Therapeutics, Inc. [MCRB] 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 (Last) (First) (Middle) C/O SERES THERAPEUTICS, INC., 200 SIDNEY STREET 3. Date of Earliest Transaction (Month/Day/Year) 06/25/2018 (Street) CAMBRIDGE, MA 02139 4. If Amendment, Date 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 (City) (State) (Zip) 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) Code V Amount (A) or (D) Price Common Stock 06/25/2018   M   16,288 A $ 0.71 255,056 D   Common Stock 06/25/2018   S(1)   26,752 D $ 9.2144 (2) 228,304 D   Common Stock 06/26/2018   M   21,224 A $ 0.71 249,528 D   Common Stock 06/26/2018   S(1)   21,224 D $ 9.194 (3) 228,304 D   Common Stock 06/27/2018   M   16,991 A $ 0.71 245,295 D   Common Stock 06/27/2018   S(1)   16,991 D $ 9.0288 (4) 228,304 D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 Underlying Securities (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 of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

STOCK OPTION (RIGHT TO BUY)

$ 0.71

06/25/2018

M

16,288

(5)

08/07/2024

COMMON STOCK

16,288

$ 0

895,153

D

STOCK OPTION (RIGHT TO BUY)

$ 0.71

06/26/2018

M

21,224

(5)

08/07/2024

COMMON STOCK

21,224

$ 0

873,929

D

STOCK OPTION (RIGHT TO BUY)

$ 0.71

06/27/2018

M

16,991

(5)

08/07/2024

COMMON STOCK

16,991

$ 0

856,938

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Pomerantz Roger C/O SERES THERAPEUTICS, INC. 200 SIDNEY STREET CAMBRIDGE, MA 02139	X		President and CEO

Signatures

/s/ Thomas J. DesRosier, Attorney-in-Fact		06/27/2018
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The sale reported in the Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 15, 2018.
(2)	The price reported is a weighted average price. The shares were sold in multiple transactions at per share prices ranging from $9.08 to $9.52. The Reporting Person undertakes to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(3)	The price reported is a weighted average price. The shares were sold in multiple transactions at per share prices ranging from $9.00 to $9.365. The Reporting Person undertakes to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(4)	The price reported is a weighted average price. The shares were sold in multiple transactions at per share prices ranging from $9.00 to $9.16. The Reporting Person undertakes to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(5)	The option vested as to 25% of the shares on June 1, 2015. The remainder of the shares have vested or will vest in 12 equal quarterly installments thereafter.

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