EOSE · Eos Energy Enterprises, Inc.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

The reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, which will vest in three installments on each of the first three anniversaries of the grant date, subject to continued service through each vesting date.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

The reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, which will vest in three installments on each of the first three anniversaries of the grant date, subject to continued service through each vesting date.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

The reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, which will vest in three installments on each of the first three anniversaries of the grant date, subject to continued service through each vesting date.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

The reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, which will vest in three installments on each of the first three anniversaries of the grant date, subject to continued service through each vesting date.

Not applicable.

The JV Warrants are governed by that certain Warrant Agreement, dated as of August 4, 2026, by and between the Issuer and Continental Stock Transfer & Trust Company, as warrant agent (the "Warrant Agreement"). The JV Warrants are immediately exercisable at an exercise price of $5.481 per share of Common Stock and expire on the tenth anniversary of the date of issuance. The JV Warrants may be exercised for cash or on a cashless basis. The Issuer may lower the exercise price and extend the duration of the JV Warrants under certain conditions described in the Warrant Agreement. The Issuer has certain rights to redeem the JV Warrants beginning five years after the date of issuance of the JV Warrants under certain conditions described in the Warrant Agreement. The JV Warrants are subject to customary anti-dilution adjustments as described in the Warrant Agreement.

On August 4, 2026, Eos Energy Enterprises Inc. (the "Issuer"), CCM Frontier JV Holdco, LLC ("CCM Frontier"), and HBC MSF Capital Solutions Blocker II LLC, an affiliate of Hudson Bay Capital Management LP ("HBC"), consummated the closing of the funding of Frontier Power USA Parent, LLC (the "JV Company"), a joint venture among the Issuer, CCM Frontier and HBC. Pursuant to a Contribution and Warrants Purchase Agreement (the "Contribution and Warrants Purchase Agreement"), dated as of August 4, 2026, by and between CCM Frontier and the JV Company, CCM Frontier (i) caused the JV Company to receive the benefit of certain contracts, contacts, investment opportunities, subject matter expertise and other going concern value with respect to the Frontier power platform developed by affiliates of CCM Frontier and (ii) contributed cash and certain assets to the JV Company as detailed in the Contribution and Warrants Purchase Agreement.

(continued from footnote 1) In exchange therefor and for certain funds previously contributed by CCM Frontier to the JV Company, the JV Company (A) issued to CCM Frontier 50,000,001 Class A-1 Units of the JV Company and 100,000,000 Class A-2 Units of the JV Company and (B) sold and transferred to CCM Frontier warrants (the "JV Warrants") to purchase 20,017,772 shares of Common Stock of the Issuer that were previously contributed to the JV Company by the Issuer. The transfer of the JV Warrants to CCM Frontier was contemplated in the agreement governing the Issuer's contribution of the JV Warrants to the JV Company.

The securities of the Issuer reported herein are held directly by CCM Frontier. CCM Frontier Power USA Holdings, LP ("CCM Frontier LP") is the sole member of CCM Frontier. CCM Frontier Power USA Holdings GP, LLC ("CCM Frontier GP") is the general partner of CCM Frontier LP. Cerberus GP Manager LLC ("Cerberus GP Manager", and together with CCM Frontier, CCM Frontier LP, and CCM Frontier GP, the "Reporting Persons") is the sole member of CCM Frontier GP. Due to their relationships with CCM Frontier, CCM Frontier LP, CCM Frontier GP, and Cerberus GP Manager may be deemed to indirectly beneficially own the securities of the Issuer held directly by CCM Frontier. The Reporting Persons are affiliates of and may be deemed to be a Section 13(d) group with CCM Denali Equity Holdings, LP, CCM Denali Equity Holdings GP, LLC and Cerberus Capital Management II, L.P., each of which has previously filed Form 3 and Form 4 filings to report beneficial ownership of securities of the Issuer.

Each of CCM Frontier LP, CCM Frontier GP and Cerberus GP Manager disclaims beneficial ownership of the securities of the Issuer held directly by CCM Frontier except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of CCM Frontier LP, CCM Frontier GP or Cerberus GP Manager is the beneficial owner of such securities for purposes of Section 16 or any other purpose.

The sales reported in this Form 4 were effected automatically pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 15, 2025 to cover estimated tax withholding obligations in connection with the vesting of restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.23 to $3.48, 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.

The sales reported in this Form 4 were effected automatically pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 15, 2025 to cover estimated tax withholding obligations in connection with the vesting of restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.23 to $3.44, 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.

Represents shares withheld from vested restricted stock unit ("RSU") award to satisfy tax obligations, as permitted by the Company's Amended and Restated 2020 Incentive Plan.

The reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, which will vest in three installments on each of the first three anniversaries of the grant date, subject to continued service through each vesting date.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

The reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, which will vest in three installments on each of the first three anniversaries of the grant date, subject to continued service through each vesting date.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

Granted as part of the Company's annual compensation review process and reflects an adjustment based on benchmarking against market compensation practices.

The reporting person was granted RSUs that settle in common stock, which will vest on the earlier of (i) the first anniversary of the grant date and (ii) immediately prior to the date of the next annual shareholders meeting of the Company following the grant date.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

Granted as part of the Company's annual compensation review process and reflects an adjustment based on benchmarking against market compensation practices.

The reporting person was granted RSUs that settle in common stock, which will vest on the earlier of (i) the first anniversary of the grant date and (ii) immediately prior to the date of the next annual shareholders meeting of the Company following the grant date.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

Granted as part of the Company's annual compensation review process and reflects an adjustment based on benchmarking against market compensation practices.

The reporting person was granted RSUs that settle in common stock, which will vest on the earlier of (i) the first anniversary of the grant date and (ii) immediately prior to the date of the next annual shareholders meeting of the Company following the grant date.

Not applicable.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Warrants became exercisable immediately after the Rights Offering closed and expire 10 years later, unless exercised or redeemed earlier. If a warrant is not exercised or redeemed before it expires, it will have no value.

Represents the conversion of a subscription right issued by the Issuer as part of a rights offering that closed on July 21, 2026 (the "Rights Offering"). Each subscription right was exercisable for units that consisted of (i) 1 share of common stock and (ii) 0.4388 of a warrant exercisable to acquire a share of common stock at an exercise price of $5.48 per share.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

The reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, which will vest in three installments on each of the first three anniversaries of the grant date, subject to continued service through each vesting date.

Not applicable.

Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock.

The reporting person was granted RSUs that settle in cash or common stock, which will vest on the earlier of (i) the first anniversary of the grant date and (ii) immediately prior to the date of the next annual shareholders meeting of the Company following the grant date.

Not applicable.

The sales reported in this Form 4 were effected automatically pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 15, 2025 to cover estimated tax withholding obligations in connection with the vesting of restricted stock units.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $4.40 to $5.24, 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.