As filed with the Securities and Exchange Commission on March 29, 2022

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Acumen Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

427 Park St.

Charlottesville, VA 22902

(434) 297-1000

(Address of principal executive offices, including zip code)

Acumen Pharmaceuticals, Inc. 2021 Equity Incentive Plan

Acumen Pharmaceuticals, Inc. 2021 Employee Stock Purchase Plan

(Full titles of the plans)

Daniel O’Connell

Chief Executive Officer

Acumen Pharmaceuticals, Inc.

427 Park St.

Charlottesville, VA 22902

(434) 297-1000

(Name, address and telephone number, including area code, of agent for service)

Copies to:

Darren DeStefano

Sarah Sellers

Katherine Denby

Cooley LLP

11951 Freedom Dr. 14th Floor

Reston, Virginia 20190

(703) 456-8039

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

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 7(a)(2)(B) of the Securities Act.  ☐

EXPLANATORY NOTE

REGISTRATION OF ADDITIONAL SHARES

Pursuant to General Instruction E of Form S-8, Acumen Pharmaceuticals, Inc. (the “Registrant”) is filing this Registration Statement on Form S-8 with the Securities and Exchange Commission (the “Commission”) for the purpose of registering (i) 2,023,663 additional shares of its common stock under the 2021 Equity Incentive Plan (the “2021 Plan”), pursuant to the provisions of the 2021 Plan providing for an automatic increase in the number of shares of common stock reserved and available for issuance under the 2021 Plan on January 1, 2022, (ii) 18,148 additional shares of its common stock under the 2021 Plan pursuant to the provisions of the 2021 Plan providing that shares subject to outstanding stock options or other stock awards that were granted under the Registrant’s 2013 Amended and Restated Stock Performance Plan (the “Prior Plan”) that terminate or expire prior to exercise or settlement, are settled in cash, are forfeited or repurchased because of the failure to vest, or are reacquired or withheld to satisfy a tax withholding obligation or the purchase or exercise price in accordance with the terms of the Prior Plan become available for issuance under the 2021 Plan, and (iii) 404,732 additional shares of its common stock under the 2021 Employee Stock Purchase Plan (the “2021 ESPP,” and together with the 2021 Plan the “Plans”), pursuant to the provisions of the 2021 ESPP providing for an automatic increase in the number of shares of common stock reserved and available for issuance under the 2021 ESPP on January 1, 2022. In accordance with the instructional note to Part I of Form S-8 as promulgated by the Commission, the information specified by Part I of the Form S-8 has been omitted from this Registration Statement.

The Registrant previously registered shares of its common stock for issuance under the Plans on a Registration Statement on Form S-8 filed with the Commission on July 2, 2021 (File No. 333-257666). Pursuant to General Instruction E to Form S-8, this Registration Statement hereby incorporates by reference the contents of the Registration Statements referenced above except as set forth below.

PART II

INFORMATION REQUIRED IN REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE

The following documents filed by the Registrant with the Commission are incorporated by reference into this Registration Statement:

deemed to be incorporated by reference herein and to be a part of this Registration Statement from the date of the filing of such reports and documents. Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any subsequently filed document that also is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.

ITEM 8. EXHIBITS

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Charlottesville, Commonwealth of Virginia, on March 29, 2022.

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Daniel O’Connell and William Matthew Zuga, and each one of them, as his or her true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him or her and in their name, place or stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this registration statement, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents or any of them, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

Exhibit 5.1

Darren DeStefano

T: +1 703 456 8034

ddestefano@cooley.com

March 29, 2022

Acumen Pharmaceuticals, Inc.

427 Park St.

Charlottesville, VA 22902

Ladies and Gentlemen:

We have represented Acumen Pharmaceuticals, Inc., a Delaware corporation (the “Company”), in connection with the filing by the Company of a Registration Statement on Form S-8 (the “Registration Statement”) with the Securities and Exchange Commission covering the offering of up to 2,446,543 shares (the “Shares”) of the Company’s common stock, par value $0.0001 per share (the “Common Stock”), consisting of (a) 2,041,811 shares of Common Stock issuable pursuant to the Company’s 2021 Equity Incentive Plan (the “2021 Plan”), and (b) 404,732 shares of Common Stock issuable pursuant to the Company’s 2021 Employee Stock Purchase Plan (together with the 2021 Plan, the “Plans”).

In connection with this opinion, we have examined and relied upon (a) the Registration Statement and the related prospectuses, (b) the Company’s Amended and Restated Certificate of Incorporation and Amended and Restated Bylaws, each as currently in effect, (c) the Plans and (d) originals or copies certified to our satisfaction of such records, documents, certificates, memoranda and other instruments as in our judgment are necessary or appropriate to enable us to render the opinion expressed below. We have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to originals of all documents submitted to us as copies, the accuracy, completeness and authenticity of certificates of public officials, and the due authorization, execution and delivery of all documents by all persons other than the Company where authorization, execution and delivery are prerequisites to the effectiveness thereof. As to certain factual matters, we have relied upon a certificate of an officer of the Company and have not independently verified such matters.

Our opinion is expressed only with respect to the General Corporation Law of the State of Delaware. We express no opinion to the extent that any other laws are applicable to the subject matter hereof and express no opinion and provide no assurance as to compliance with any federal or state securities law, rule or regulation.

On the basis of the foregoing, and in reliance thereon, we are of the opinion that the Shares, when sold and issued in accordance with the Plans, the Registration Statement and the related prospectuses, will be validly issued, fully paid and nonassessable (except as to shares issued pursuant to certain deferred payment arrangements, which will be fully paid and nonassessable when such deferred payments are made in full).

Cooley LLP    Reston Town Center    11951 Freedom Drive    14th Floor    Reston, VA    20190-5656

t: +1 703 456 8000 f: +1 703 456 8100 cooley.com

Acumen Pharmaceuticals, Inc.

March 29, 2022

Page Two

We consent to the filing of this opinion as an exhibit to the Registration Statement.

Sincerely,

Cooley LLP

Cooley LLP    Reston Town Center    11951 Freedom Drive    14th Floor    Reston, VA    20190-5656

t: +1 703 456 8000 f: +1 703 456 8100 cooley.com

Exhibit 23.2

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the Registration Statement (Form S-8), dated March 29, 2022, pertaining to the Acumen Pharmaceuticals Inc. 2021 Equity Incentive Plan and 2021 Employee Stock Purchase Plan of our report dated March 28, 2022, with respect to the consolidated financial statements of Acumen Pharmaceuticals Inc., included in its Annual Report (Form 10-K) for the year ended December 31, 2021 filed with the Securities and Exchange Commission.

/s/ Ernst & Young LLP

Tysons, Virginia

March 28, 2022

Exhibit 107

CALCULATION OF FILING FEE TABLES

Form S-8

Acumen Pharmaceuticals, Inc.

Table 1: Newly Registered Securities