LifeStance Health Group Inc. American IPO prospectus (Version as of 2026-02-27)

LifeStance Health Group, Inc.Common Stock The selling stockholders identified in this prospectus supplement are offering 25,000,000 shares of common stock, par value $0.01 per share (the“common stock”), of LifeStance Health Group, Inc. (the “Company”). The Company is not selling any shares of common stock under this prospectus Subject to the completion of this offering, we intend to purchase from the underwriter 7,000,000 shares of our common stock that are subject tothis offering at a price per share equal to the price per share paid by the underwriter to the selling stockholders in this offering (the “Share Repurchase”).The repurchased shares of common stock will no longer be outstanding after this offering. The underwriter will not receive any compensation for theshares of our common stock being purchased by us. The offering is not conditioned upon the completion of the Share Repurchase. We cannot assure you The Company’s common stock is listed on the Nasdaq Global Select Market (“Nasdaq”) under the symbol “LFST.” On February24, 2026, the lastsale price of the common stock as reported on Nasdaq was $7.14 per share. The underwriter has agreed to purchase shares of common stock from the selling stockholders at a price of $7.01per share, which will resultin $175,250,000 of proceeds to the selling stockholders before expenses. The underwriter may offer the shares of common stock offered by thisprospectus supplement, other than shares subject to the Share Repurchase, from time to time at market prices prevailing at the time of sale, at pricesrelated to such prevailing market prices, at negotiated prices, at fixed prices or at prices that may be subject to change. The underwriter may effect Investing in the Company’s common stock involves risks. See “Risk Factors” beginning on page S-4 and in thedocuments incorporated by reference herein. Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense. The underwriter expects to deliver the shares of common stock on or about March2, 2026, through the book-entry facilities of The DepositoryTrust Company. J.P. Morgan The date of this prospectus supplement is February25, 2026. TABLE OF CONTENTS Prospectus Supplement ABOUT THIS PROSPECTUS SUPPLEMENTWHERE YOU CAN FIND MORE INFORMATION; INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCECAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSPROSPECTUS SUPPLEMENT SUMMARYTHE OFFERINGRISK FACTORSUSE OF PROCEEDSSELLING STOCKHOLDERSMATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS TO NON-U.S. HOLDERSUNDERWRITINGLEGAL MATTERSEXPERTS Prospectus ABOUT THIS PROSPECTUSWHERE YOU CAN FIND MORE INFORMATION; INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS THE COMPANYRISK FACTORSUSE OF PROCEEDSSELLING STOCKHOLDERSDESCRIPTION OF CAPITAL STOCKPLAN OF DISTRIBUTIONLEGAL MATTERS ABOUT THIS PROSPECTUS SUPPLEMENT This document consists of two parts. The first part is this prospectus supplement, which describes the specific terms of this offering andsupplements information contained in the accompanying prospectus and the documents incorporated by reference in this prospectus supplement and theaccompanying prospectus. The second part is the accompanying prospectus, which describes more general information, some of which may not apply tothis offering. You should read both this prospectus supplement and the accompanying prospectus, including the documents incorporated by reference Any statement made in this prospectus supplement, the accompanying prospectus or in a document incorporated or deemed to be incorporated byreference in this prospectus supplement or in the accompanying prospectus will be deemed to be modified or superseded to the extent that a statementcontained in this prospectus supplement or in any other document subsequently filed with the SEC that is also incorporated or deemed to beincorporated by reference in this prospectus supplement modifies or supersedes that statement. Any statement so modified or superseded will not bedeemed, except as so modified or superseded, to constitute a part of this prospectus supplement. See “Where You Can Find More Information;Incorporation of Certain Documents by Reference.” In various places in this prospectus supplement and the accompanying prospectus, we refer you to We are responsible for the information contained in this prospectus supplement, the accompanying prospectus and any permitted free writingprospectus. None of the Company, any selling stockholder or any underwriter has authorized anyone to provide you with any different or additionalinformation or to make any representations about information that is not contained or incorporated by reference in this prospectus supplement, any None of the Company, any selling sto