UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of report (Date of earliest event reported): March 18, 2020

SERES THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

200 Sidney Street

Cambridge, MA 02139

(Address of principal executive offices) (Zip Code)

(617) 945-9626

(Registrant’s telephone number, include area code)

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☒

Item 1.01 Entry into a Material Definitive Agreement

On March 18, 2020, Seres Therapeutics, Inc. (the “Company”, “we” and “our”) entered into a Sales Agreement (the “Sales Agreement”) with Cowen and Company, LLC (“Cowen”) to sell shares of the Company’s common stock, par value $0.001 per share (the “Common Stock”), with aggregate gross sales proceeds of up to $25,000,000, from time to time, through an “at the market” equity offering program under which Cowen will act as sales agent.

Under the Sales Agreement, the Company will set the parameters for the sale of shares, including the number of shares to be issued, the time period during which sales are requested to be made, limitations on the number of shares that may be sold in any one trading day and any minimum price below which sales may not be made. Subject to the terms and conditions of the Sales Agreement, Cowen may sell the shares by methods deemed to be an “at the market offering” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”), including sales made through The Nasdaq Global Select Market, on any other existing trading market for the Common Stock or to or through a market maker. The Company will pay Cowen a commission equal to up to 3.0% of the gross proceeds of any Common Stock sold through Cowen under the Sales Agreement, and also has provided Cowen with customary indemnification rights. The Sales Agreement may be terminated by the Company upon ten days’ prior notice to Cowen or by Cowen upon ten days’ prior notice to the Company, or at any time under certain circumstances, including but not limited to the occurrence of a material adverse change in the Company.

Any sales of shares under the Sales Agreement will be made pursuant to the Company’s shelf registration statement on Form S-3 (File No. 333-237033) filed with the Securities and Exchange Commission (the “Commission”) on March 9, 2020, which became effective on March 18, 2020. The Company filed a prospectus supplement with the Commission on March 18, 2020 in connection with the offer and sale of the shares pursuant to the Sales Agreement.

The foregoing description of the material terms of the Sales Agreement is qualified in its entirety by reference to the full agreement, a copy of which is filed as Exhibit 1.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Latham & Watkins LLP, counsel to the Company, has issued an opinion to the Company, dated March 18, 2020, regarding the validity of the shares of Common Stock to be issued and sold pursuant to the Sales Agreement. A copy of the opinion is filed as Exhibit 5.1 to this Current Report on Form 8-K.

This Current Report on Form 8-K shall not constitute an offer to sell or the solicitation of any offer to buy the securities discussed herein, nor shall there be any offer, solicitation or sale of the securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.

Item 8.01 Other Events.

The Company is updating its Risk Factors to add the following:

The outbreak of the novel strain of coronavirus, COVID-19, could adversely impact our business, including our preclinical studies and clinical trials.

In December 2019, a novel strain of coronavirus, COVID-19, surfaced in Wuhan, China. Since then, COVID-19 has spread to multiple countries, including the United States. In response to the spread of COVID-19, we have closed our executive offices with our administrative employees continuing their work outside of our offices, restricted on-site staff to only those required to execute their job responsibilities and limited the number of staff in any given research and development laboratory. As a result of the COVID-19 outbreak, we may experience disruptions that could severely impact our business, preclinical studies and clinical trials, including:

In addition, the trading prices for our common stock and other biopharmaceutical companies have been highly volatile as a result of the COVID-19 epidemic. As a result, we may face difficulties raising capital through sales of our common stock or such sales may be on unfavorable terms. The COVID-19 outbreak continues to rapidly evolve. The extent to which the outbreak may impact our business, preclinical studies and clinical trials will depend on future developments, which are highly uncertain and cannot be predicted with confidence, such as the ultimate geographic spread of the disease, the duration of the outbreak, travel restrictions and social distancing in the United States and other countries, business closures or business disruptions and the effectiveness of actions taken in the United States and other countries to contain and treat the disease.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.