# EDGAR Filing Document

**Accession Number:** 0001833275
**File Stem:** 0001628280-25-055938
**Filing Date:** 2025-12
**Character Count:** 9501
**Document Hash:** 0b05cbadf76b87423014e7cf52f1089e
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001628280-25-055938.hdr.sgml**: 20251208

**ACCESSION NUMBER**: 0001628280-25-055938

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20251205

**FILED AS OF DATE**: 20251208

**DATE AS OF CHANGE**: 20251208

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Stidolph Russell Monoki
- **CENTRAL INDEX KEY:** 0001833275

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-39291
- **FILM NUMBER:** 251557436

**MAIL ADDRESS:**
- **STREET 1:** 137 ROWAYTON AVENUE
- **CITY:** ROWAYTON
- **STATE:** CT
- **ZIP:** 06853
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Eos Energy Enterprises, Inc.
- **CENTRAL INDEX KEY:** 0001805077
- **STANDARD INDUSTRIAL CLASSIFICATION:** MISCELLANEOUS ELECTRICAL MACHINERY, EQUIPMENT & SUPPLIES [3690]
- **ORGANIZATION NAME:** 04 Manufacturing
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 3920 PARK AVENUE
- **CITY:** EDISON
- **STATE:** NJ
- **ZIP:** 08820
- **BUSINESS PHONE:** (732) 225-8400

**MAIL ADDRESS:**
- **STREET 1:** 3920 PARK AVENUE
- **CITY:** EDISON
- **STATE:** NJ
- **ZIP:** 08820

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** B. Riley Principal Merger Corp. II
- **DATE OF NAME CHANGE:** 20200227

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

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

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Stidolph Russell Monoki<br><sub>(Last) (First) (Middle)</sub><br>C/O ALTENERGY LLC<br>137 ROWAYTON AVENUE<br><sub>(Street)</sub><br>ROWAYTON, CT 06853<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-12-05 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[X] Director [ ] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Eos Energy Enterprises, Inc. [ EOSE ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2025-12-05 |  | S |  | 500000 | D | $14.99 | 2153272 | I | See footnote<sup>(1)</sup> |
| Common Stock | 2025-12-08 |  | S |  | 29999 | D | 15.36<sup>(2)</sup> | 2123273 | I | See footnote<sup>(1)</sup> |
| Common Stock | 2025-12-05 |  | J<sup>(3)</sup> |  | 75000 | D | $0 | 2048273 | I | See footnote<sup>(1)</sup> |
| Common Stock | 2025-12-05 |  | J<sup>(3)</sup> |  | 75000 | A | $0 | 439355 | D |  |
| Common Stock | 2025-12-05 |  | G |  | 60000<sup>(4)</sup> | D | $0 | 379355 | D |  |
| Common Stock | 2025-12-05 |  | G |  | 15000<sup>(5)</sup> | D | $0 | 364355 | D |  |
| Common Stock | 2025-12-08 |  | M |  | 30788 | A | $14.43 | 395143 | D |  |
| Common Stock | 2025-12-08 |  | F |  | 30020 | D | $14.80 | 365123 | D |  |
| Common Stock | 2025-12-08 |  | S |  | 768 | D | $14.80 | 364355 | D |  |
| Common Stock | 2025-12-08 |  | M |  | 145018 | A | $1.18 | 509373 | D |  |
| Common Stock | 2025-12-08 |  | M |  | 120633 | A | $2.32 | 630006 | D |  |
| Common Stock | 2025-12-08 |  | F |  | 18793 | D | 14.89<sup>(6)</sup> | 611213 | D |  |
| Common Stock | 2025-12-08 |  | F |  | 11491 | D | 14.89<sup>(6)</sup> | 599722 | D |  |
| Common Stock | 2025-12-08 |  | S |  | 235367 | D | 14.89<sup>(6)</sup> | 364355 | D |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Stock Option (Right to Buy) | $14.43 | 2025-12-08 |  | M |  |  | 30788 | <sup>(7)</sup> | 2025-12-08 | Common Stock | 30788 | $0 | 0 | D |  |
| Stock Option (Right to Buy) | $1.18 | 2025-12-08 |  | M |  |  | 145018 | <sup>(8)</sup> | 2027-05-19 | Common Stock | 145018 | $0 | 0 | D |  |
| Stock Option (Right to Buy) | $2.32 | 2025-12-08 |  | M |  |  | 120633 | <sup>(9)</sup> | 2028-05-18 | Common Stock | 120633 | $0 | 0 | D |  |

---

### Footnotes:

(1) The shares reported in this Form 4 are shares of common stock in which Mr. Stidolph has a pecuniary interest in that are held directly by AltEnergy, LLC or AltEnergy Transmission, LLC.  Mr. Stidolph is the managing director of AltEnergy, LLC and the managing member of AltEnergy Transmission, LLC and has voting and dispositive power with respect to the securities owned by AltEnergy, LLC and AltEnergy Transmission, LLC. 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.

(2) The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.28 to $15.45, inclusive. The reporting person undertakes to provide the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above.

(3) Represents the receipt, for no consideration, of an aggregate of 75,000 shares of Common Stock of the Issuer by AltEnergy pursuant to pro rata distribution by AltEnergy.

(4) Represents a charitable donation by the reporting person.

(5) Reflects the donation of common stock to a charitable donor advised fund.

(6) The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions pursuant to a Cashless exercise / same-day sale at prices ranging from $14.68 to $15.16, inclusive. The reporting person undertakes to provide the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above.

(7) On December 8, 2020 the reporting person was granted stock options to purchase 30,788 shares of common stock which vested on June 15, 2021.

(8) On May 19, 2022 the reporting person was granted stock options to purchase 145,018 shares of common stock which vested on May 19, 2023.

(9) On May 18, 2023 the reporting person was granted stock options to purchase 120,633 shares of common stock which vested on April 30, 2024.

**Signature:** /s/ Michael Silberman as attorney-in-fact for Russell Stidolph  
**Date:** 2025-12-08

### Remarks:

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).

** 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.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**