As filed with the Securities and Exchange Commission on July 23, 2026 

Registration No. 333-  

UNITED STATES 

SECURITIES AND EXCHANGE COMMISSION 

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT 

UNDER THE SECURITIES ACT OF 1933

EOS ENERGY ENTERPRISES, INC. 

(Exact name of registrant as specified in its charter)

Two Allegheny Center

Nova Tower 2

Pittsburgh, Pennsylvania 15212 

(Address of principal executive offices, including zip code)

Registrant’s telephone number, including area code: (732) 225-8400

Second Amended and Restated 2020 Incentive Plan 

(Full title of the plans)

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

Copies to

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 the “large accelerated filer,” “accelerated filer,” “non-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 13(a) of the Exchange Act. ☐

REGISTRATION OF ADDITIONAL SHARES 

PURSUANT TO GENERAL INSTRUCTION E

Pursuant to General Instruction E of Form S-8, Eos Energy Enterprises, Inc. (“Registrant”) is filing this Registration Statement on Form S-8 with the U.S. Securities and Exchange Commission (the “Commission”) to register 5,000,000 additional shares of the Registrant’s Common Stock for issuance under the Eos Energy Enterprises, Inc. Second Amended and Restated 2020 Incentive Plan (“2020 Plan”). This Registration Statement hereby incorporates by reference the contents of the Registrant’s registration statements on Form S-8 filed with the Commission on June 4, 2021 (Registration No. 333-256766), June 17, 2022 (Registration No. 333-265708), June 23, 2023 (Registration No. 333- 272848), June 26, 2024 (Registration No. 333-280506) and June 26, 2025 (Registration No. 333-288331). 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 Form S-8 has been omitted from this Registration Statement.

PART II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

We hereby incorporate by reference into this registration statement the following documents previously filed with the Commission:

(a) The Registrant’s Annual Report on Form 10-K for the fiscal year ended December 31, 2025, filed with the Commission on February 26, 2026 (File No. 001-39291) (the “Annual Report”);

(b) All other reports filed pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), since the end of the fiscal year covered by the Annual Report (other than the portions of these documents not deemed to be filed); and

(c) The description of the Common Stock contained in Exhibit 4.2 to the Registrant’s Annual Report, including any amendment or report filed for the purpose of updating such description.

All documents filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act on or after the date of this Registration Statement and prior to the filing of a post-effective amendment to this Registration Statement that indicates that all securities offered have been sold or that deregisters all securities then remaining unsold shall be deemed to be incorporated by reference in this Registration Statement and to be part hereof from the date of filing of such documents; provided, however, that documents or information deemed to have been furnished and not filed in accordance with the rules of the Commission shall not be deemed incorporated by reference into this Registration Statement. 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 which 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 5. Interests of Named Experts and Counsel.

Not applicable.

Item 8. Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, 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 Pittsburgh, State of Pennsylvania, on July 23, 2026.

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Joe Mastrangelo, Alessandro Lagi and Marie Batz Martin, and each of them, his or her true and lawful attorneys-in-fact and agents, each with full power of substitution and resubstitution, for him or her and in his or her name, place and 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 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, as fully for all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that each of said attorneys-in-fact and agents, 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 Exchange Act of 1933, this report has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated.

ATTACHMENTS / EXHIBITS

EXHIBIT 5.1

EXHIBIT 23.1

EXHIBIT 99.3

EX-FILING FEES

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