Failure to Satisfy Listing Rule - Form 8-K

Item 3.01. Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing.

On April 19, 2024, Seres Therapeutics, Inc. (the "Company") received a letter from the Listing Qualifications Department of The Nasdaq Stock Market LLC ("Nasdaq") notifying the Company that, for the last 30 consecutive business days, the bid price for the Company's common stock, par value $0.001 per share (the "Common Stock"), had closed below the $1.00 per share minimum bid price requirement for continued inclusion on The Nasdaq Global Select Market pursuant to Nasdaq Listing Rule 5450(a)(1) (the "Bid Price Requirement").

The letter has no immediate effect on the listing of the Common Stock on The Nasdaq Global Select Market, and the Common Stock will continue to trade on The Nasdaq Global Select Market under the symbol "MCRB," subject to the Company's compliance with the other continued listing requirements of The Nasdaq Global Select Market. In accordance with Nasdaq Listing Rule 5810(c)(3)(A), the Company has been provided an initial compliance period of 180 calendar days from receipt of the letter, or until October 16, 2024, to regain compliance with the Bid Price Requirement. To regain compliance, the closing bid price for the Common Stock must be at least $1.00 per share for a minimum of 10 consecutive business days prior to October 16, 2024. There can be no assurance that the Company will be able to regain compliance or that Nasdaq will extend the compliance period.

If the Company does not regain compliance with the Bid Price Requirement by October 16, 2024, the Company may be eligible for an additional 180 calendar day compliance period. To qualify, the Company must submit an application to transfer the listing of the Common Stock to The Nasdaq Capital Market, which requires the Company to meet the continued listing requirement for the market value of publicly held shares and all other initial listing standards for The Nasdaq Capital Market, other than the Bid Price Requirement. The Company would also need to pay an application fee to Nasdaq and to provide written notice of its intention to cure the deficiency during the additional compliance period. As part of its review process, Nasdaq will make a determination of whether it believes the Company will be able to cure this deficiency.

If the Company does not regain compliance within the applicable compliance period(s), the Company expects that Nasdaq will provide written notification to the Company that the Common Stock will be subject to delisting. At that time, the Company may appeal the delisting determination to a Nasdaq Listing Qualifications Panel.

The Company intends to monitor the closing bid price of the Common Stock and may, if appropriate, consider taking actions to regain compliance with the Bid Price Requirement, including, subject to approval of the Company's Board of Directors and its stockholders, implementing a reverse stock split.

There can be no assurance that the Company will be able to regain compliance with the Bid Price Requirement or will otherwise be in compliance with other applicable Nasdaq listing rules within the applicable compliance period(s), that the Company will be able to successfully implement a reverse stock split, or, if the Company receives a delisting determination and decides to appeal the delisting determination, that such appeal would be successful.

Forward-Looking Statements Disclaimer

This Current Report contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this Current Report on Form 8-Kthat do not relate to matters of historical fact should be considered forward-looking statements, including statements regarding the Company's intent or ability to transfer the listing of its common stock to The Nasdaq Capital Market, regain compliance with any applicable Nasdaq listing requirements, implement a reverse stock split, or the timing of any of the foregoing. These forward-looking statements are based on the Company's management's current expectations. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause the Company's actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to the factors discussed under the caption "Risk Factors" in our Annual Report on Form 10-Kfiled with the Securities and Exchange Commission (SEC), on March 5, 2024, and our other reports filed with the SEC could cause actual results to differ materially from those indicated by the forward-looking

statements made in this Current Report. Any such forward-looking statements represent management's estimates as of the date of this Current Report. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this Current Report.