Advantage Solutions Inc — 8-K exhibit

Exhibit 3.1

CERTIFICATE OF AMENDMENT

TO

THIRD AMENDED AND RESTATED CERTIFICATE OF INCORPORATION

OF

ADVANTAGE SOLUTIONS INC.

Pursuant to Section 242 of the

General Corporation Law of the State of Delaware

Advantage Solutions Inc., a Delaware corporation (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware, does hereby certify as follows:

RESOLVED, that the first paragraph of Article IV of the Third Amended and Restated Certificate of Incorporation of the Corporation, as amended and/or restated to date, be amended and restated in its entirety to read as follows:

“That, effective as of 5 p.m. Eastern Time on the date this Certificate of Amendment to Amended and Restated Certificate of Incorporation is filed with the Office of the Secretary of State of the State of Delaware (the “Effective Time”), a one-for-twenty-five reverse stock split of the Corporation’s Common Stock (as defined below) shall become effective, pursuant to which each twenty-five shares of Common Stock outstanding and held of record by each stockholder of the Corporation (including treasury shares) immediately prior to the Effective Time shall be reclassified and combined into one validly issued, fully-paid and nonassessable share of Common Stock automatically and without any action by the holder thereof upon the Effective Time and shall represent one share of Common Stock from and after the Effective Time (such reclassification and combination of shares, the “Reverse Stock Split”). The par value of the Common Stock following the Reverse Stock Split shall remain at $0.0001 per share. No fractional shares of Common Stock shall be issued as a result of the Reverse Stock Split. In lieu thereof, (i) with respect to holders of one or more certificates which formerly represented shares of Common Stock that were issued and outstanding immediately prior to the Effective Time, upon surrender after the Effective Time of such certificate or certificates, any holder who would otherwise be entitled to a fractional share of Common Stock as a result of the Reverse Stock Split, following the Effective Time, shall be entitled to receive a cash payment (the “Fractional Share Payment”) equal to the fraction of which such holder would otherwise be entitled multiplied by the closing price per share as reported by The Nasdaq Global Select Market (as adjusted to give effect to the Reverse Stock Split) on the date of the Effective Time; provided that, whether or not fractional shares would be issuable as a result of the Reverse Stock Split shall be determined on the basis of (a) the total number of shares of Common Stock that were issued and outstanding immediately prior to the Effective Time formerly represented by certificates that the holder is at the time surrendering and (b) the aggregate

number of shares of Common Stock after the Effective Time into which the shares of Common Stock formerly represented by such certificates shall have been reclassified; and (ii) with respect to holders of shares of Common Stock in book-entry form in the records of the Corporation’s transfer agent that were issued and outstanding immediately prior to the Effective Time, any holder who would otherwise be entitled to a fractional share of Common Stock as a result of the Reverse Stock Split, following the Effective Time, shall be entitled to receive the Fractional Share Payment automatically and without any action by the holder.

The total number of shares of all classes of capital stock which the Corporation shall have authority to issue is 198,000,000 shares, consisting of 197,400,000 shares of Class A common stock, par value $0.0001 per share (the “Common Stock”), and 600,000 shares of undesignated preferred stock, par value $0.0001 per share (the “Preferred Stock”).

IN WITNESS WHEREOF, this Certificate of Amendment to Third Amended and Restated Certificate of Incorporation has been executed by a duly authorized officer of the Corporation on this 26th day of March, 2026.

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