Seres Therapeutics, Inc. — Director's Dealing 2016

May 6, 2016

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Seres Therapeutics, Inc. (MCRB)
CIK: 0001609809
Period of Report: 2016-05-04

Reporting Person: Pomerantz Roger (Director, President and CEO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2016-05-04	Common Stock	M	28598	$0.71	Acquired	51325	Direct
2016-05-04	Common Stock	S	28598	$26.52	Disposed	22727	Direct
2016-05-04	Common Stock	M	700	$0.71	Acquired	23427	Direct
2016-05-04	Common Stock	S	700	$27.31	Disposed	22727	Direct
2016-05-05	Common Stock	M	21127	$0.71	Acquired	43854	Direct
2016-05-05	Common Stock	S	21127	$25.48	Disposed	22727	Direct
2016-05-05	Common Stock	M	8900	$0.71	Acquired	31627	Direct
2016-05-05	Common Stock	S	8900	$26.34	Disposed	22727	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2016-05-04	Stock Option (right to buy)	$0.71	M	29298	Disposed	2024-08-07	Common Stock (29298)	Direct
2016-05-05	Stock Option (right to buy)	$0.71	M	30027	Disposed	2024-08-07	Common Stock (30027)	Direct

Footnotes

F1: The sale reported in the Form 4 was effected pursuant to a Rule 10b5 1 trading plan adopted by the Reporting Person on February 26, 2016.

F2: The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $26.14 to $27.13. 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.

F3: The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $27.165 to $27.49. 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.

F4: The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $25.07 to $26.035. 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.

F5: The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $26.07 to $26.64. 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.

F6: The option vested as to 25% of the shares subject to the option on June 1, 2015. The remainder of the shares have vested or will vest in 12 equal quarterly installments thereafter.