SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* Cerberus GP Manager LLC (Last) (First) (Middle) 875 THIRD AVENUE 11TH FLOOR (Street) NEW YORK NEW YORK 10022 (City) (State) (Zip) UNITED STATES (Country)	2. Date of Event Requiring Statement (Month/Day/Year) 08/04/2026	3. Issuer Name and Ticker or Trading Symbol Eos Energy Enterprises, Inc. [ EOSE ]
		3a. Foreign Trading Symbol	5. If Amendment, Date of Original Filed (Month/Day/Year)
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner Officer (give title below) Other (specify below)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* Cerberus GP Manager LLC (Last) (First) (Middle) 875 THIRD AVENUE 11TH FLOOR (Street) NEW YORK NEW YORK 10022 (City) (State) (Zip) UNITED STATES (Country) Relationship of Reporting Person(s) to Issuer X Director 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* CCM Frontier JV Holdco, LLC (Last) (First) (Middle) 875 THIRD FLOOR 11TH FLOOR (Street) NEW YORK NEW YORK 10022 (City) (State) (Zip) UNITED STATES (Country) Relationship of Reporting Person(s) to Issuer X Director 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* CCM Frontier Power USA Holdings, LP (Last) (First) (Middle) 875 THIRD AVENUE 11TH FLOOR (Street) NEW YORK NEW YORK 10022 (City) (State) (Zip) UNITED STATES (Country) Relationship of Reporting Person(s) to Issuer X Director 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* CCM Frontier Power USA Holdings GP, LLC (Last) (First) (Middle) 875 THIRD AVENUE 11TH FLOOR (Street) NEW YORK NEW YORK 10022 (City) (State) (Zip) UNITED STATES (Country) Relationship of Reporting Person(s) to Issuer X Director 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

Remarks:

Nicholas P. Robinson and Nathaniel Fick, each an employee of an affiliate of the Reporting Persons, and David Urban are directors of Eos Energy Enterprises, Inc. (the "Issuer"). By virtue of their representation on the board of directors of the Issuer, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, the Reporting Persons are deemed directors by deputization of the Issuer.

No securities are beneficially owned.

	CERBERUS GP MANAGER LLC, By: /s/ Alexander D. Benjamin/Senior Managing Director	08/06/2026
	CCM FRONTIER JV HOLDCO, LLC, By: /s/ Jake Hansen/President	08/06/2026
	CCM FRONTIER POWER USA HOLDINGS, LP, By: /s/ Jake Hansen/President	08/06/2026
	CCM FRONTIER POWER USA HOLDINGS GP, LLC, By: /s/ Jake Hansen/President	08/06/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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* Form 3: SEC 1473 (03-26)