Sec Form 4 Filing - Stidolph Russell Monoki @ Eos Energy Enterprises, Inc. - 2021-03-02

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Stidolph Russell Monoki 2. Issuer Name and Ticker or Trading Symbol Eos Energy Enterprises, Inc. [ EOSE] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O ALTENERGY LLC, 137 ROWAYTON AVENUE 3. Date of Earliest Transaction (MM/DD/YY) 03/02/2021 (Street) ROWAYTON, CT06853 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 03/02/2021 J( 1 ) 92,375 D $ 0 7,135,109 I See footnotes ( 2 ) ( 3 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Stidolph Russell Monoki C/O ALTENERGY LLC 137 ROWAYTON AVENUE ROWAYTON, CT06853 X X AltEnergy, LLC 137 ROWAYTON AVENUE ROWAYTON, CT06853 X AltEnergy Storage II LLC 137 ROWAYTON AVENUE ROWAYTON, CT06853 X AltEnergy Storage V LLC 137 ROWAYTON AVENUE ROWAYTON, CT06853 X AltEnergy Storage VI LLC 137 ROWAYTON AVENUE ROWAYTON, CT06853 X AltEnergy Storage Bridge LLC 137 ROWAYTON AVENUE ROWAYTON, CT06853 X AltEnergy Transmission LLC 137 ROWAYTON AVENUE ROWAYTON, CT06853 X AltEnergy Storage Bridge Phase II LLC 137 ROWAYTON AVENUE ROWAYTON, CT06853 X Signatures /s/ Russell Stidolph 03/04/2021 Signature of Reporting Person Date AltEnergy LLC by: /s/ Russell Stidolph, Managing Director 03/04/2021 Signature of Reporting Person Date AltEnergy Storage II LLC by: /s/ Russell Stidolph, Managing Director 03/04/2021 Signature of Reporting Person Date AltEnergy Storage V LLC by: /s/ Russell Stidolph, Managing Director 03/04/2021 Signature of Reporting Person Date AltEnergy VI LLC by: /s/ Russell Stidolph, Managing Director 03/04/2021 Signature of Reporting Person Date AltEnergy Storage Bridge LLC by: /s/ Russell Stidolph, Managing Director 03/04/2021 Signature of Reporting Person Date AltEnergy Transmission LLC by: /s/ Russell Stidolph, Managing Director 03/04/2021 Signature of Reporting Person Date AltEnergy Storage Bridge Phase II LLC by: /s/ Russell Stidolph, Managing Director 03/04/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )AltEnergy Storage Bridge Phase II, LLC and AltEnergy Storage Bridge, LLC made pro rata distributions for no consideration of an aggregate of 92,375 shares of Common Stock of the Issuer to their respective members on March 2, 2021. ( 2 )In addition to Russell Stidolph, a natural person ("Mr. Stidolph"), this Form 4 is being filed jointly by AltEnergy LLC, a Delaware limited liability company ("AltEnergy"); (ii) AltEnergy Storage LLC, a Delaware limited liability company ("AltEnergy I"); (iii) AltEnergy Storage II LLC, a Delaware limited liability company ("AltEnergy II"); (iv) AltEnergy Storage V LLC, a Delaware limited liability company ("AltEnergy V"); (v) AltEnergy VI LLC, a Delaware limited liability company ("AltEnergy VI"); AltEnergy Storage Bridge LLC, a Delaware limited liability company ("Bridge"); AltEnergy Transmission LLC, a Delaware limited liability company ("Transmission"); AltEnergy Storage Bridge Phase II LLC ("Bridge II" and collectively, the "Filing Persons"). ( 3 )The shares reported in this Form 4 are shares of common stock in which Mr. Stidoloph has a pecuniary interest in that are held directly byAltEnergy I, AltEnergy II, AltEnergy V, AltEnergy VI, Bridge, Transmission or Bridge II. Mr. Stidolph is the managing director of AltEnergy, the managing member of each of AltEnergy I, AltEnergy II, AltEnergy V, AltEnergy VI, Bridge, Transmission and Bridge II, and has voting and dispositive power with respect to the securities owned by AltEnergy I, AltEnergy II, AltEnergy V, AltEnergy VI, Bridge, Transmission and Bridge II. Each of the Filing Persons disclaims beneficial ownership of the outstanding shares of common stock of the issuer reported herein except to the extent of its pecuniary interest therein.

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 4(b)(v).

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