Filed Pursuant to Rule 424(b)(3)
Registration No. 333-282450

PROSPECTUS

Seres Therapeutics, Inc.

14,285,715 Shares of Common Stock

This prospectus relates to the resale, from time to time, of up to 14,285,715 shares of our common stock, or the shares, by the selling stockholder identified in this prospectus, or the selling stockholder.

We will not receive any proceeds from the sale of the shares by the selling stockholder.

We will bear all costs, expenses and fees in connection with the registration of the shares of common stock. The selling stockholder will bear all commissions and discounts, if any, attributable to its sales of the shares.

Our common stock is listed on The Nasdaq Global Select Market under the symbol “MCRB”. On October 10, 2024, the closing sale price of our common stock as reported on The Nasdaq Global Select Market was $0.77.

Our business and investment in our common stock involve significant risks. These risks are described in the section titled “Risk Factors” beginning on page 6 of this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is October 11, 2024.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS	1
WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE	2
THE COMPANY	4
THE OFFERING	5
RISK FACTORS	6
USE OF PROCEEDS	7
DESCRIPTION OF CAPITAL STOCK	8
SELLING STOCKHOLDER	11
PLAN OF DISTRIBUTION	12
LEGAL MATTERS	14
EXPERTS	14

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ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement filed with the U.S. Securities and Exchange Commission, or the SEC, using a “shelf” registration process. By using a shelf registration statement, the selling stockholder may, from time to time, sell the shares in one or more offerings as described in this prospectus. When the selling stockholder offers and sells the shares, we or the selling stockholder may provide a prospectus supplement to this prospectus that contains specific information about the securities being offered and sold and the specific terms of that offering. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. The prospectus supplement or free writing prospectus may also add, update or change information contained in this prospectus with respect to that offering. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement or free writing prospectus, you should rely on the prospectus supplement or free writing prospectus, as applicable. Before purchasing any securities, you should carefully read both this prospectus and the applicable prospectus supplement (and any applicable free writing prospectuses), together with the additional information described under the heading “Where You Can Find More Information; Incorporation by Reference.”

Neither we, nor the selling stockholder, have authorized anyone to provide you with any information or to make any representations other than those contained in this prospectus, any applicable prospectus supplement or any free writing prospectuses prepared by or on behalf of us or to which we have referred you. We and the selling stockholder take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. The selling stockholder will not make an offer to sell the shares in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus and the applicable prospectus supplement to this prospectus is accurate only as of the date on its respective cover, that the information appearing in any applicable free writing prospectus is accurate only as of the date of that free writing prospectus, and that any information incorporated by reference is accurate only as of the date of the document incorporated by reference, unless we indicate otherwise. Our business, financial condition, results of operations and prospects may have changed since those dates. This prospectus incorporates by reference, and any prospectus supplement or free writing prospectus may contain and incorporate by reference, market data and industry statistics and forecasts that are based on independent industry publications and other publicly available information. Although we believe these sources are reliable, we do not guarantee the accuracy or completeness of this information and we have not independently verified this information. In addition, the market and industry data and forecasts that may be included or incorporated by reference in this prospectus, any prospectus supplement or any applicable free writing prospectus may involve estimates, assumptions and other risks and uncertainties and are subject to change based on various factors, including those discussed under the heading “Risk Factors” contained in this prospectus, the applicable prospectus supplement and any applicable free writing prospectus, and under similar headings in other documents that are incorporated by reference into this prospectus. Accordingly, investors should not place undue reliance on this information.

When we refer to “Seres,” “we,” “our,” “us” and the “Company” in this prospectus, we mean Seres Therapeutics, Inc. and its consolidated subsidiaries, unless otherwise specified. When we refer to “you,” we mean the potential holders of the shares.

We own or have rights to trademarks, trade names and service marks that we use in connection with the operation of our business. In addition, our name, logos and website name and address are our trademarks or service marks. Solely for convenience, in some cases, the trademarks, trade names and service marks referred to in this offering memorandum are listed without the applicable ^®, ^™ and SM symbols, but we will assert, to the fullest extent under applicable law, our rights to these trademarks, trade names and service marks. Other trademarks, trade names and service marks appearing in this prospectus are the property of their respective owners.

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WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE

Available Information

We file reports, proxy statements and other information with the SEC. The SEC maintains a web site that contains reports, proxy and information statements and other information about issuers, such as us, who file electronically with the SEC. The address of that website is http://www.sec.gov.

Our web site address is https://www.serestherapeutics.com. The information on our web site, however, is not, and should not be deemed to be, a part of this prospectus.

This prospectus and any prospectus supplement are part of a registration statement that we filed with the SEC and do not contain all of the information in the registration statement. The full registration statement may be obtained from the SEC or us, as provided below. Documents establishing the terms of the offered securities are or may be filed as exhibits to the registration statement or documents incorporated by reference in the registration statement. Statements in this prospectus or any prospectus supplement about these documents are summaries and each statement is qualified in all respects by reference to the document to which it refers. You should refer to the actual documents for a more complete description of the relevant matters. You may inspect a copy of the registration statement through the SEC’s website, as provided above.

Incorporation by Reference

The SEC’s rules allow us to “incorporate by reference” information into this prospectus, which means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus, and subsequent information that we file with the SEC will automatically update and supersede that information. Any statement contained in this prospectus or a previously filed document incorporated by reference will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or a subsequently filed document incorporated by reference modifies or replaces that statement.

This prospectus and any accompanying prospectus supplement incorporate by reference the documents set forth below that have previously been filed with the SEC, excluding in each case any information furnished to, rather than filed with, the SEC:

• Our Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed with the SEC on March 5, 2024;

• The information specifically incorporated by reference into our Annual Report on Form 10-K from our Definitive Proxy Statement on Schedule 14A, filed with the SEC on March 5, 2024;

• Our Quarterly Reports on Form 10-Q for the fiscal quarters ended March 31, 2024 and June 30, 2024, filed with the SEC on May 8, 2024 and August 13, 2024, respectively;

• Our Current Reports on Form 8-K filed with the SEC on  January  2, 2024, January 30, 2024,  February 26, 2024,  April 8, 2024,  April 23, 2024,  May 7, 2024,  August  6, 2024, September  12, 2024, September  26, 2024 and October 1, 2024; and

• The description of our Common Stock contained in our Registration Statement on Form 8-A, dated and filed with the SEC on June 22, 2015, and any amendment or report filed with the SEC for the purpose of updating the description.

All reports and other documents we subsequently file pursuant to Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, which we refer to as the “Exchange Act” in this prospectus, prior to the termination of this offering, but excluding any information furnished to, rather than filed with, the SEC, will also be incorporated by reference into this prospectus and deemed to be part of this prospectus from the date of the filing of such reports and documents.

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You may request a free copy of any of the documents incorporated by reference in this prospectus by writing or telephoning us at the following address:

Seres Therapeutics, Inc.

101 Cambridgepark Drive

Cambridge, MA 02140

(617) 945-9626

Exhibits to the filings will not be sent, however, unless those exhibits have specifically been incorporated by reference in this prospectus or any accompanying prospectus supplement.

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THE COMPANY

We are a commercial-stage company focused on improving patient outcomes in medically vulnerable populations through novel live biotherapeutics. Our first drug, VOWST, formerly called SER-109, was approved by the U.S. Food and Drug Administration on April 26, 2023 to prevent recurrence of Clostridioides difficile infection, or CDI, in patients 18 or older following antibacterial treatment for recurrent CDI. We launched VOWST in the United States with our collaborator, Nestlé Health Science in June 2023. On August 5, 2024, we entered into an Asset Purchase Agreement with Société des Produits Nestlé S.A., or SPN, a wholly-owned subsidiary of Nestlé S.A., pursuant to which we sold our VOWST microbiome therapeutic business to SPN and its designated affiliates on September 30, 2024. We are now focusing on advancing SER-155 and our other wholly-owned cultivated live biotherapeutic candidates to improve patient outcomes for medically vulnerable patient populations with potential to address large commercial opportunities.

Corporate Information

We were incorporated in the State of Delaware in 2010 under the name Newco LS21, Inc. In October 2011, we changed our name to Seres Health, Inc., and in May 2015, we changed our name to Seres Therapeutics, Inc. Our principal executive offices are located at 101 Cambridgepark Drive, Cambridge, MA 02140 and our telephone number is (617) 945-9626. Our website address is www.serestherapeutics.com. The information contained in, or accessible through, our website does not constitute a part of this prospectus.

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THE OFFERING

Issuer Seres Therapeutics, Inc.

Shares of Common Stock Offered by the Selling Stockholder Up to 14,285,715 shares.

Use of Proceeds We will not receive any proceeds from the sale of shares of common stock by the selling stockholder.

Market for Common Stock Our common stock is listed on The Nasdaq Global Select Market under the symbol “MCRB”.

Risk Factors Investing in our common stock involves a high degree of risk. See “Risk Factors” beginning on page 6 of this prospectus for a discussion of factors you should carefully consider before investing in our common stock.

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RISK FACTORS

Investment in any securities offered pursuant to this prospectus and the applicable prospectus supplement involves risks. You should carefully consider the risk factors incorporated by reference to our most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q or Current Reports on Form 8-K, and all other information contained or incorporated by reference into this prospectus, as updated by our subsequent filings under the Exchange Act, and the risk factors and other information contained in the applicable prospectus supplement and any applicable free writing prospectus before acquiring any of such securities. The occurrence of any of these risks might cause you to lose all or part of your investment in the offered securities.

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USE OF PROCEEDS

We will not receive any proceeds from the sale of shares of common stock by the selling stockholder.

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DESCRIPTION OF CAPITAL STOCK

General

The following description of the capital stock of Seres Therapeutics, Inc. (the “Company,” “we,” “us,” and “our”) and certain provisions of our Restated Certificate of Incorporation, as amended (“Certificate of Incorporation”) and Amended and Restated Bylaws (“Bylaws”) are summaries and are qualified in their entirety by reference to the applicable provisions of our Certificate of Incorporation and Bylaws, which have been publicly filed with the Securities and Exchange Commission. We encourage you to read our Certificate of Incorporation, our Bylaws and the applicable provisions of the General Corporation Law of the State of Delaware for more information.

Capital Stock

Our authorized capital stock consists of 360,000,000 shares of common stock, par value $0.001 per share, and 10,000,000 shares of preferred stock, par value $0.001 per share.

Common Stock

Voting Rights. Holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of stockholders and do not have cumulative voting rights. An election of directors by our stockholders shall be determined by a plurality of the votes cast by the stockholders entitled to vote on the election. Subject to the supermajority votes for some matters, other matters shall be decided by the affirmative vote of our stockholders having a majority in voting power of the votes cast by the stockholders present or represented and voting on such matter. Our Certificate of Incorporation and Bylaws also provide that our directors may be removed only for cause and only by the affirmative vote of the holders of at least two-thirds in voting power of the outstanding shares of capital stock entitled to vote thereon. In addition, the affirmative vote of the holders of at least two-thirds in voting power of the outstanding shares of capital stock entitled to vote thereon is required to amend or repeal, or to adopt any provision inconsistent with, several of the provisions of our Certificate of Incorporation. Holders of common stock are entitled to receive proportionately any dividends as may be declared by our board of directors, subject to any preferential dividend rights of any series of preferred stock that we may designate and issue in the future.

Rights Upon Liquidation. In the event of our liquidation or dissolution, the holders of common stock are entitled to receive proportionately our net assets available for distribution to stockholders after the payment of all debts and other liabilities and subject to the prior rights of any outstanding preferred stock.

Other Rights. Holders of common stock have no preemptive, subscription, redemption or conversion rights. The rights, preferences and privileges of holders of common stock are subject to and may be adversely affected by the rights of the holders of shares of any series of preferred stock that we may designate and issue in the future.

Dividend

Holders of common stock are entitled to receive proportionately any dividends as may be declared by our board of directors, subject to any preferential dividend rights of outstanding preferred stock. We have never declared or paid any cash dividends on our capital stock. We do not intend to pay cash dividends for the foreseeable future. We currently expect to retain all future earnings, if any, for use in the development, operation and expansion of our business. Any determination to pay cash dividends in the future will depend upon, among other things, our results of operations, plans for expansion, tax considerations, available net profits and reserves, limitations under law, financial condition, capital requirements and other factors that our board of directors considers to be relevant.

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Preferred Stock

Under the terms of our Certificate of Incorporation, our board of directors is authorized to direct us to issue shares of preferred stock in one or more series without stockholder approval. Our board of directors has the discretion to determine the rights, preferences, privileges and restrictions, including voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences, of each series of preferred stock.

The purpose of authorizing our board of directors to issue preferred stock and determine its rights and preferences is to eliminate delays associated with a stockholder vote on specific issuances. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions, future financings and other corporate purposes, could have the effect of making it more difficult for a third party to acquire, or could discourage a third party from seeking to acquire, a majority of our outstanding voting stock. There are no shares of preferred stock outstanding, and we have no present plans to issue any shares of preferred stock.

Anti-Takeover Effects of Delaware Law and Our Certificate of Incorporation and Bylaws

Some provisions of Delaware law, our Certificate of Incorporation and our Bylaws could make the following transactions more difficult: an acquisition of us by means of a tender offer; an acquisition of us by means of a proxy contest or otherwise; or the removal of our incumbent officers and directors. It is possible that these provisions could make it more difficult to accomplish or could deter transactions that stockholders may otherwise consider to be in their best interest or in our best interest, including transactions which provide for payment of a premium over the market price for our shares.

These provisions, summarized below, are intended to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to encourage persons seeking to acquire control of us to first negotiate with our board of directors. We believe that the benefits of the increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure us outweigh the disadvantages of discouraging these proposals because negotiation of these proposals could result in an improvement of their terms.

Undesignated Preferred Stock. The ability of our board of directors, without action by the stockholders, to issue up to 10,000,000 shares of undesignated preferred stock with voting or other rights or preferences as designated by our board of directors could impede the success of any attempt to effect a change in control of us. These and other provisions may have the effect of deferring hostile takeovers or delaying changes in control or management of our company.

Stockholder Meetings. Our Bylaws provide that a special meeting of stockholders may be called only by our chairperson of the board, chief executive officer or president (in the absence of a chief executive officer), or by a resolution adopted by a majority of our board of directors.

Requirements for Advance Notification of Stockholder Nominations and Proposals. Our Bylaws establish advance notice procedures with respect to stockholder proposals to be brought before a stockholder meeting and the nomination of candidates for election as directors, other than nominations made by or at the direction of the board of directors or a committee of the board of directors.

Elimination of Stockholder Action by Written Consent. Our Certificate of Incorporation eliminates the right of stockholders to act by written consent without a meeting.

Staggered Board. Our board of directors is divided into three classes. The directors in each class will serve for a three-year term, one class being elected each year by our stockholders. This system of electing and removing directors may tend to discourage a third party from making a tender offer or otherwise attempting to obtain control of us, because it generally makes it more difficult for stockholders to replace a majority of the directors.

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Removal of Directors. Our Certificate of Incorporation provides that no member of our board of directors may be removed from office by our stockholders except for cause and, in addition to any other vote required by law, upon the approval of the holders of at least two-thirds in voting power of the outstanding shares of stock entitled to vote in the election of directors.

Stockholders Not Entitled to Cumulative Voting. Our Certificate of Incorporation does not permit stockholders to cumulate their votes in the election of directors. Accordingly, the holders of a majority of the outstanding shares of our common stock entitled to vote in any election of directors can elect all of the directors standing for election, if they choose, other than any directors that holders of our preferred stock may be entitled to elect.

Delaware Anti-Takeover Statute. We are subject to Section 203 of the General Corporation Law of the State of Delaware, which prohibits persons deemed to be “interested stockholders” from engaging in a “business combination” with a publicly held Delaware corporation for three years following the date these persons become interested stockholders unless the business combination is, or the transaction in which the person became an interested stockholder was, approved in a prescribed manner or another prescribed exception applies. Generally, an “interested stockholder” is a person who, together with affiliates and associates, owns, or within three years prior to the determination of interested stockholder status did own, 15% or more of a corporation’s voting stock. Generally, a “business combination” includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. The existence of this law may have an anti-takeover effect with respect to transactions not approved in advance by the board of directors.

Choice of Forum. Our Certificate of Incorporation provides that, unless we consent in writing to the selection of an alternative form, the Court of Chancery of the State of Delaware will be the sole and exclusive forum for: (1) any derivative action or proceeding brought on our behalf; (2) any action asserting a claim of breach of a fiduciary duty or other wrongdoing by any of our directors, officers, employees or agents to us or our stockholders; (3) any action asserting a claim against us arising pursuant to any provision of the General Corporation Law of the State of Delaware or Certificate of Incorporation or Bylaws; or (4) any action asserting a claim governed by the internal affairs doctrine. In addition, our Bylaws provide that the federal district courts of the United States are the exclusive forum for any complaint raising a cause of action arising under the Securities Act. Any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock will be deemed to have notice of and to have consented to these choice of forum provisions. It is possible that a court of law could find the choice of forum provisions contained in our Certificate of Incorporation or Bylaws to be inapplicable or unenforceable if challenged in a proceeding or otherwise.

Amendment of Certificate of Incorporation. The amendment of any of the above provisions in our Certificate of Incorporation, except for the provision making it possible for our board of directors to issue preferred stock and the provision prohibiting cumulative voting, would require approval by holders of at least two-thirds in voting power of the outstanding shares of stock entitled to vote thereon.

The provisions of Delaware law, our Certificate of Incorporation and our amended and restated bylaws could have the effect of discouraging others from attempting hostile takeovers and, as a consequence, they may also inhibit temporary fluctuations in the market price of our common stock that often result from actual or rumored hostile takeover attempts. These provisions may also have the effect of preventing changes in the composition of our board and management. It is possible that these provisions could make it more difficult to accomplish transactions that stockholders may otherwise deem to be in their best interest.

Transfer Agent and Registrar

The transfer agent and registrar for the common stock is Equiniti Trust Company, LLC.

Trading Symbol and Market

Our common stock is listed on The Nasdaq Global Select Market under the symbol “MCRB”.

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SELLING STOCKHOLDER

On August 5, 2024, we entered into an Asset Purchase Agreement with SPN pursuant to which we sold our VOWST microbiome therapeutic business to SPN and its designated affiliates on September 30, 2024. As a condition to closing of the Asset Purchase Agreement, we and SPN entered into a Securities Purchase Agreement pursuant to which, on September 30, 2024, SPN purchased 14,285,715 shares of our common stock, or the Shares, at a purchase price per Share of $1.05, for an aggregate purchase price of approximately $15 million. This prospectus covers the resale or other disposition from time to time by the selling stockholder and its pledgees, donees, transferees, assignees or other successors-in-interest that receive Shares after the date of this prospectus of the Shares.

The following table sets forth the name of the selling stockholder, the number of shares beneficially owned by the selling stockholder, the number of Shares that may be offered under this prospectus, and the number of shares beneficially owned by the selling stockholder assuming all of the Shares registered for resale hereby are sold. The number of shares in the column “Number of Shares Being Offered” represents all of the Shares that the selling stockholder may offer under this prospectus. The selling stockholder may sell some, all or none of the Shares. Other than as set forth in the SPA, we have no agreements, arrangements or understandings with the selling stockholder regarding the sale or other disposition of any of the Shares.

The number of shares beneficially owned by the selling stockholder is determined under rules issued by the SEC. Under these rules, beneficial ownership includes any shares as to which an individual or entity has sole or shared voting power or investment power. Percentage ownership is based on 170,200,253 shares of common stock outstanding as of September 30, 2024. In computing the number of shares beneficially owned by the selling stockholder and the percentage ownership of the selling stockholder, shares of common stock subject to options or other rights held by the selling stockholder that are currently exercisable or will become exercisable within 60 days of September 30, 2024 are considered outstanding.

Grégory Behar, Chief Executive Officer of Nestlé Health Science, a business unit of SPN, served as a member of our Board of Directors from December 2014 until October 2023. Additionally, pursuant to the SPA, for so long as SPN together with its affiliates beneficially owns at least 10% of our outstanding shares of common stock, we shall take such actions within our control to include in the slate of nominees, recommended by our Board of Directors and/or the applicable committee thereof, for election as directors at each applicable annual or special meeting of stockholders at which directors are to be elected, one individual designated by SPN. Other than the foregoing, the selling stockholder does not have, nor has it had within the past three years, any position, office or other material relationship with us.

	Shares Beneficially Owned Prior to the Offering					Number of Shares		Shares Beneficially Owned After the Offering
Name of Selling Stockholder	Number of Shares		Percentage			Being Offered		Number of Shares		Percentage
Société des Produits Nestlé S.A.(1)		21,781,753		12.8	%		14,285,715		7,496,038		4.4	%

(1) Based on a Schedule 13D/A filed on July 22, 2022 by Nestlé S.A. (“Nestlé”) and SPN and information known to us. The ultimate parent company of SPN is Nestlé. Nestlé has shared voting and dispositive power with respect to the shares held by SPN. The address for Nestlé and SPN is Avenue Nestlé 55, 1800, Vevey Switzerland.

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PLAN OF DISTRIBUTION

The selling stockholder and any of its pledgees, donees, transferees, assignees or other successors-in-interest may, from time to time, sell, transfer or otherwise dispose of any or all of the Shares or interests in the Shares on any stock exchange, market or trading facility on which the Shares are traded or in private transactions. These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market price, at varying prices determined at the time of sale, or at negotiated prices. The selling stockholder may use any one or more of the following methods when disposing of the Shares or interests therein:

• distributions to members, partners, stockholders or other equityholders of the selling stockholder;

• ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;

• block trades in which the broker-dealer so engaged will attempt to sell the Shares as agent but may position and resell a portion of the block as principal to facilitate the transaction;

• to or through broker-dealers or underwriters;

• purchases by a broker-dealer as principal and resale by such broker-dealer for its own account pursuant to this prospectus;

• an exchange distribution in accordance with the rules of the applicable exchange;

• in “at the market” offerings, as defined in Rule 415 under the Securities Act, at negotiated prices, at prices prevailing at the time of sale or at prices related to such prevailing market prices, including sales made directly on a national securities exchange or sales made through a market maker other than on an exchange or other similar offerings through sales agents;

• privately negotiated transactions;

• through the writing or settlement of options or other hedging transactions whether through an options exchange or otherwise;

• broker-dealers may agree with the selling stockholder to sell a specified number of such shares at a stipulated price per share;

• a combination of any of the above methods of disposition; or

• any other method permitted pursuant to applicable law.

The selling stockholder may also sell the Shares under Rule 144 or Rule 904 under the Securities, if available, or Section 4(a)(1) under the Securities Act, rather than under this prospectus.

Broker-dealers engaged by the selling stockholder may arrange for other broker-dealers to participate in sales. Broker-dealers may receive commissions or discounts from the selling stockholder (or, if any broker-dealer acts as agent for the purchaser of shares, from the purchaser) in amounts to be negotiated. The selling stockholder does not expect these commissions and discounts to exceed what is customary in the types of transactions involved.

The selling stockholder may, from time to time, pledge or grant a security interest in some or all of the shares of common stock owned by it, including the Shares, and, if it defaults in the performance of its secured obligations, the pledgees or secured parties may offer and sell such shares from time to time under this prospectus, or under a supplement or amendment to this prospectus under Rule 424(b)(7) or other applicable provision of the Securities Act amending the list of selling stockholders to include the pledgee, transferee or other successors in interest as selling stockholders under this prospectus.

Upon being notified in writing by the selling stockholder that any material arrangement has been entered into with a broker-dealer for the sale of Shares through a block trade, special offering, exchange distribution or

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secondary distribution or a purchase by a broker or dealer, we will file a supplement to this prospectus, if required, pursuant to Rule 424(b) under the Securities Act, disclosing (i) the name of each such selling stockholder and of the participating broker-dealer(s), (ii) the number of Shares involved, (iii) the price at which such Shares were sold, (iv) the commissions paid or discounts or concessions allowed to such broker-dealer(s), where applicable, (v) that such broker-dealer(s) did not conduct any investigation to verify the information set out or incorporated by reference in this prospectus, and (vi) other facts material to the transaction. In addition, upon being notified in writing by the selling stockholder that a donee or pledgee intends to sell more than 500 Shares, we will file a supplement to this prospectus if then required in accordance with applicable securities law.

The selling stockholder also may transfer the Shares in other circumstances, in which case the transferees, pledgees or other successors in interest will be the selling beneficial owners for purposes of this prospectus.

In connection with the sale of the Shares or interests therein, the selling stockholder may enter into hedging transactions with broker-dealers or other financial institutions, which may in turn engage in short sales of our common stock in the course of hedging the positions they assume. The selling stockholder may also sell shares of our common stock short and deliver these securities to close out its short positions, or loan or pledge our common stock to broker-dealers that in turn may sell these securities. The selling stockholder may also enter into option or other transactions with broker-dealers or other financial institutions or the creation of one or more derivative securities which require the delivery to such broker-dealer or other financial institution of Shares, which Shares such broker-dealer or other financial institution may resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).

The selling stockholder and any broker-dealers or agents that are involved in selling the Shares may be deemed to be “underwriters” within the meaning of the Securities Act in connection with such sales. In such event, any profits realized by the selling stockholder or compensation received by such broker-dealers or agents may be deemed to be underwriting commissions or discounts under the Securities Act. The maximum commission or discount to be received by any member of the Financial Industry Regulatory Authority (FINRA) or independent broker-dealer will not be greater than 8% of the initial gross proceeds from the sale of any security being sold.

We have advised the selling stockholder that it is required to comply with Regulation M promulgated under the Exchange during such time as it may be engaged in a distribution of the Shares. The foregoing may affect the marketability of our common stock.

The aggregate proceeds to the selling stockholder from the sale of the Shares will be the purchase price of the Shares less discounts or commissions, if any. The selling stockholder reserves the right to accept and, together with its agents from time to time, to reject, in whole or in part, any proposed purchase of common stock to be made directly or through agents. We will not receive any of the proceeds from this offering.

We shall pay all fees and expenses incident to the registration of the Shares.

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LEGAL MATTERS

Latham & Watkins LLP will pass upon certain legal matters relating to the issuance and sale of the shares offered hereby on behalf of Seres Therapeutics, Inc. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

The financial statements incorporated in this Prospectus by reference to the Annual Report on Form 10-K for the year ended December 31, 2023 have been so incorporated in reliance on the report (which contains an explanatory paragraph relating to the Company’s ability to continue as a going concern as described in Note 1 to the financial statements) of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

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