Eos Energy Enterprises reported $82.73 million revenue

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For the quarterly period ended June September 30, 2026

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Indicate by check mark whether the registrant has submitted electronically and posted on its corporate web site, website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes ☒ No ☐

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The registrant had outstanding 364,167,744 366,363,999 shares of common stock as of August November 3, 2026.

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Financial statements 4 changes

Unaudited Condensed Consolidated Balance Sheets as of June September 30, 2026 and December 31, 2025

Unaudited Condensed Consolidated Statements of Operations and Comprehensive Incom e (Loss) Income for the Three and Six Nine Months Ended June September 30, 2026 and 2025

Unaudited Condensed Consolidated Statements of Shareholders' Deficit for the Three and Six Nine Months Ended June September 30, 2026 and 2025

Unaudited Condensed Consolidated Statements of Cash Flows for the Six Nine Months Ended June September 30, 2026 and 2025

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Exhibits 607 changes

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• our customers' ability to secure project financing;

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Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements. Forward-looking statements speak only as of the date they are made. Readers are cautioned not to put undue reliance on forward-looking statements and, except as required by law, the Company (as defined below) assumes no obligation and does not intend to update or revise these forward-looking statements, whether as a result of new information, future events, or otherwise. See also Part I, Item 1A, "Risk Factors" disclosures contained in the Company's Annual Report on Form 10-K for the year ended December 31, 2025 for additional discussion of the risks and uncertainties that could cause the Company's actual results to differ materially from those expressed or implied in its forward-looking statements.

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Restricted cash 43,579 34,636

Vendor deposits 16,118 11,756

Prepaid expenses 3,243 2,701

Cash and cash equivalents $ 305,491 271,162 $ 567,992

Restricted cash 57,923 34,636

Accounts receivable, net 8,117 8,673 6,779

Accounts receivable - related party 5,516 109 —

Vendor deposits 20,797 11,756

Contract assets, current 15,877 18,156 13,972

Contract assets, current - related party 4,405 —

Prepaid expenses 4,128 2,701

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Other current assets 7,243 590

Other current assets 2,976 590

Total current assets 514,000 514,041 708,480

Property, plant and equipment, net 177,453 190,515 114,415

Intangible assets, net 1,507 1,657 979

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Operating lease right-of-use asset, net 20,727 27,347 20,420

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Total assets $ 906,779 $ 885,197

Investment in joint venture 297,642 —

Total assets $ 1,068,485 $ 885,197

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Accounts payable $ 105,598 $ 99,915

Accrued expenses 42,469 25,794

Accounts payable $ 90,478 $ 99,915

Accrued expenses 45,215 25,794

Operating lease liability, current 1,781 2,065 1,960

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Contract liabilities, current 7,912 7,521 14,975

Contract liabilities, current - related party 9,756 $ —

Other current liabilities 126 153 524

Total current liabilities 157,886 155,188 143,540

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Operating lease liability 21,926 28,804 19,182

Long-term debt 453,835 546,547 662,467

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Contract liabilities, long-term 1,974 3,723 2,506

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Other liabilities 36,044 427

Deferred tax liability 4,671 —

Other liabilities 542 427

Other liabilities - related party 22,700 —

Total long-term liabilities 1,066,455 909,563 1,618,977

Total liabilities 1,224,341 1,064,751 1,762,517

COMMITMENTS AND CONTINGENCIES (NOTE 15)

SERIES B PREFERRED STOCK - related party 463,746 1,361,542

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COMMITMENTS AND CONTINGENCIES (NOTE 15)

SERIES B PREFERRED STOCK - related party 713,222 1,361,542

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Common stock, $ 0.0001 par value, 800,000,000 shares authorized, 340,592,001 365,758,222 and 337,132,374 shares outstanding on June September 30, 2026 and December 31, 2025, respectively

Additional paid in capital 1,406,730 1,809,917 427,722

Accumulated deficit ( 2,302,646 2,193,669 ) ( 2,535,819 )

Accumulated other comprehensive loss - related party ( 134,897 76,290 ) ( 130,807 )

Accumulated other comprehensive (loss) income ( 3 4 ) 10

Total shareholders' deficit ( 1,030,784 460,012 ) ( 2,238,862 )

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June 30, Six Months Ended

Revenue $ 13,741 $ 15,236 $ 70,704 $ 25,693

Revenue - related party 55,034 — 55,034 —

Total revenue 68,775 15,236 125,738 25,693

Cost of goods sold 117,576 46,189 218,966 81,185

Research and development expenses 10,505 7,201 21,224 14,038

Selling, general and administrative expenses 24,500 25,488 48,595 46,483

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME (In thousands, except share and per share amounts) (LOSS)

(In thousands, except share and per share amounts)

September 30, Nine Months Ended

Revenue $ 14,284 $ 30,512 $ 84,988 $ 56,205

Revenue - related party 68,447 — 123,481 —

Total revenue 82,731 30,512 208,469 56,205

Cost of goods sold 126,934 64,437 345,900 145,622

Research and development expenses 10,910 6,925 32,134 20,963

Selling, general and administrative expenses 23,819 19,786 72,414 66,269

Loss from write-down of property, plant and equipment 5 205 76 766 108 585 184 1,351

Restructuring expenses 281 — 281 —

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Operating income (loss) ( 83,811 ) ( 63,847 ) ( 163,123 ) ( 116,779 )

Operating income (loss) ( 79,321 ) ( 61,221 ) ( 242,444 ) ( 178,000 )

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Interest expense ( 11,972 ) ( 2,980 ) ( 24,214 ) ( 3,958 )

Interest expense - related parties

Interest income 3,654 851 6,441 1,665

Interest expense ( 12,989 ) ( 6,007 ) ( 37,203 ) ( 9,965 )

Interest income (expense) - related parties — 840 — ( 9,451 )

Interest income 2,930 1,161 9,371 2,826

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Change in fair value of derivatives ( 70,447 ) 13,222 — 95,488 108,710 —

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Other income (expense) 206 ( 606 ) 203 ( 1,166 )

(Loss) income before income taxes ( 275,697 ) ( 222,931 ) $ 233,191 $ ( 207,790 )

Income tax expense 13 6 18 11

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and 527 more changes in the filing

Legal proceedings 146 changes

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On March 25, 2026, a shareholder derivative lawsuit (the "Skaff Complaint") was filed in the United States District Court for the District of New Jersey by plaintiff Ronald F. Skaff against certain defendants including the Company's Chief Executive Officer, the Company's then-acting Chief Financial Officer, and nine of the Company's then-

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On March 25, 2026, a shareholder derivative lawsuit (the "Skaff Complaint") was filed in the United States District Court for the District of New Jersey by plaintiff Ronald F. Skaff against certain defendants including the Company's Chief Executive Officer, the Company's then acting Chief Financial Officer, and nine of the Company's then current Directors (the "Skaff Defendants"). The Skaff Complaint alleges that the Skaff Defendants breached their fiduciary duties to the Company by allowing the Company to make knowingly false or misleading statements about the Company's manufacturing capabilities and financial outlook. The Skaff Complaint seeks declaratory relief, unspecified corporate governance reforms, and compensatory damages, including interest thereon and attorney's fees.

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Three Months Ended June 30, Six Months Ended June 30,

Restricted stock units $ 5,533 $ 5,863 $ 10,790 $ 9,345

Stock-based compensation expense included in the Unaudited Condensed Consolidated Statements of Operations and Comprehensive (Loss) Income (Loss) was as follows:

September 30, Nine Months Ended

Restricted stock units $ 6,300 $ 4,134 $ 17,090 $ 13,479

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Total $ 6,183 $ 7,127 $ 12,085 $ 14,701

Total $ 6,942 $ 4,963 $ 19,027 $ 19,664

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Eligible employees are granted restricted stock that generally vest over three years from the date of grant. Under the directors plan, restricted stock generally vest one year from the date of grant. As of June September 30, 2026, there was $ 35,645 41,203 of unrecognized compensation expense attributable to unvested RSUs, expected to be recognized over a weighted-average remaining vesting period of 2.1 2.2 years.

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During the second quarter of 2025, the Company granted shares contingent upon the achievement of certain performance targets for fiscal year 2025 and continued employment through the vesting period.

During the third quarter of 2024, the Company granted contingent shares to select key executives that may be earned based on the Company's total shareholder return ("TSR") over a two and three-year period following the grant date ("2024 TSR Awards"). During the second quarter of 2025, the Company also granted contingent shares to select key employees that may be earned based on the Company's TSR over three individual one-year periods and a cumulative three-year period following the grant date ("2025 TSR Awards"). During the third quarter of 2026, the Company also granted contingent shares to select key employees that may be earned based on the Company's TSR over three individual one-year periods and a cumulative three-year period following the grant date ("2026 TSR Awards").

TSR awards are paid out in stock at the end of the vesting period based on the Company's stock performance. The performance of the 2024 TSR Awards and 2025 TSR Awards is measured by determining the percentile rank of the total shareholder return of the Company's common stock relative to the TSR of the Russell 2000 index peer group. for the two and three-year period following the grant date. This peer group includes the entire Russell 2000 index as it existed at the beginning of the performance period, excluding any companies that were removed from the index during the performance period. The payment of awards following the two and three-year award period is based on performance achieved in accordance with the scale set forth in the plan agreement and may range from 0 % to 200 % of the initial grant. The fair value of the TSR awards is estimated using a Monte Carlo simulation in an option pricing framework.

The performance of the 2026 TSR Awards is measured by determining the percentile rank of the total shareholder return of the Company's common stock relative to the TSR of the CIBC Atlas Clean Energy Index, focusing on the U.S. companies. This peer group includes all of the US companies in the CIBC Atlas Clean Energy Index as it existed at the beginning of the performance period, excluding any companies that were removed from the index during the performance period.

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The payment of awards is based on performance achieved in accordance with the scale set forth in the plan agreement and may range from 0 % to 200 % of the initial grant. The fair value of the TSR awards is estimated using a Monte Carlo simulation in an option pricing framework.

Estimation of the 2026 TSR Awards is done on a correlated basis, incorporating the pairwise correlations between the Company and the peer group companies. The following summarizes the key assumptions used to estimate the fair value of the 2026 TSR Awards that were granted, and the resulting weighted average grant date fair value.

Company share price $ 3.46

Company volatility 120.0 %

Company dividend yield — %

Weighted average performance term 2.2 Years

Weighted average risk-free interest rate 4.2 %

Peer group average volatility 75.2 %

Weighted average grant date fair value $ 4.95

As of June September 30, 2026, there was $ 2,669 10,181 of unrecognized compensation expense attributable to unvested PRSUs, expected to be recognized over a weighted-average remaining vesting period of 1.7 2.4 years.

Income tax expense was $ 1,462 and $ 1,480 for the three and nine months ended September 30, 2026, respectively, attributable to earnings from foreign operations and income tax expense recognized from the Company's outside basis difference in the ownership interest in FPUSA. Income tax expense was $ 4 and $ 15 for the three and nine months ended September 30, 2025, respectively, related to taxable earnings from foreign operations.

Income tax expense was $ 13 and $ 6 for The three months ended June 30, 2026 and 2025, and $ 18 and $ 11 for the six months ended June 30, 2026 and 2025, respectively, related to taxable earnings from foreign operations. The income tax expense differs from the amount computed by applying the statutory U.S. federal income tax rate of 21% to the loss before income taxes. This is due attributable to fair value adjustments - derivatives and warrants, Section 162(m) disallowance, foreign operations and pre-tax losses for which no tax benefit can be recognized for U.S. income tax purposes.

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At each balance sheet date, management assesses the likelihood that the Company will be able to realize its deferred tax assets Management considered by considering all available positive and negative evidence. in assessing the need for a valuation allowance. The Realization of deferred tax assets depends on the generation of sufficient taxable income of the appropriate character and in the appropriate taxing jurisdiction during the future periods in which the related temporary differences become deductible. In evaluating the realizability of its deferred tax assets as of September 30, 2026 and December 31, 2025, management has considered cumulative losses, the scheduled reversal of deferred tax liabilities, projected future taxable income, and available tax-planning strategies. Based on this assessment, management determined that it is unlikely more likely than not that the Company will be able to utilize not realize its U.S. deferred tax assets at June 30, 2026 and December 31, 2025 due to cumulative losses. therefore the Company has maintained a valuation allowance against its net U.S. deferred tax assets. During the three and nine months ended September 30, 2026, however, the Company released a portion of its valuation allowance related to deferred tax assets attributable to existing net operating losses, resulting in income tax expense of $ 1,438 . The release was attributable to the Company's outside basis difference in its ownership interest in FPUSA, which provided a source of taxable income supporting realization of the related deferred tax assets.

As of June September 30, 2026 and December 31, 2025, the Company has unrecognized tax benefits associated with uncertain tax positions that, if recognized, would not affect the effective tax rate on income from continuing operations. The Company is currently under examination by the IRS related to tax year 2022. The Company is not under examination by any other taxing jurisdictions.

EOS ENERGY ENTERPRISES, INC.

NOTES TO THE UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (In thousands, except share and per share amounts)

17. Income Taxes (cont.)

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The Company recorded treasury stock of $ 1,081 for the three and six months ended June 30, 2026, respectively, for shares withheld from employees to cover options exercise costs and payroll tax liabilities. The treasury stock was immediately retired.

The Company is authorized to issue 1,000,000 shares of preferred stock with such designations, voting and other rights and preferences as may be determined from time to time by the Company's Board of Directors. The preferred stock has a par value of $ 0.0001 . As of June September 30, 2026 and December 31, 2025, there were no shares of preferred stock issued or outstanding.

On June 3, 2026 at the annual meeting of stockholders, stockholders of the Company approved the amendment to the Company's Certificate of Incorporation to increase the number of shares of authorized common stock from 600,000,000 to 800,000,000 at $ 0.0001 par value . The holders of the Company's common stock are entitled to one vote for each share held. At June September 30, 2026 and December 31, 2025, there were 340,592,001 365,758,222 and 337,132,374 , shares of common stock issued and outstanding, respectively.

Registered Direct Offering

On July 1, 2026, the Company closed its Registered Direct Offering pursuant to which it issued 13,683,634 shares of common stock and 6,004,378 warrants, each warrant exercisable for one share of common stock at an exercise price of $ 5.481 per share, to HBMF. The Company received aggregate net proceeds from the Registered Direct Offering of approximately $ 74,900 . The warrants issued for the Registered Direct Offering were liability classified on June 30, 2026 as the HBMF SPA included a most favored nation provision that could result in an adjustment to the settlement amount of the warrants. An adjustment would be recognized if equity was issued at a more economically favorable terms or conditions.The warrants issued in the Registered Direct Offering meet the requirements for equity classification guidance in ASC 815-40.

On July 2, 2026, the Company announced the launch of the rights offering (the "Rights Offering"), under which shareholders of Eos common stock and holders of its warrants to purchase common stock issued on April 14, 2023, May 17, 2023, December 19, 2023, and November 21, 2025 as of the record date of 5:00 p.m. Eastern time on July 1, 2026 (collectively, "Eligible Holders"), would receive rights to acquire a certain number of units, comprised of the Company's common stock and warrants (the "Units") to fund the Company's previously announced capital contribution in the FPUSA joint venture. The Company recognized $ 2,264 in Additional paid in capital and reduction of Accumulated deficit related to the bonus element arising from the rights' exercise price being below the fair value of the Units. This was a pro rata distribution to equity holders of the Company's securities and recognized as a dividend.

The Rights Offering expired at 5:00 p.m. Eastern Time on July 21, 2026 (the "Expiration Date"). Upon expiration of the Rights Offering, the most favored nation provision included within the HBMF SPA expired on the Expiration Date. As such, the liability required remeasurement through the Expiration Date, the Company recognized within the Change in fair value of derivatives on the Company's Consolidated Statements of Operations and Comprehensive Income (Loss) a $ 13,222 gain for the three month period ended September 30, 2026. On the Expiration Date, the Company reclassified $ 21,496 into Additional paid in capital as the warrants meet equity classification under ASC 815.

On August 3, 2026, the Company closed the Rights Offering pursuant to which the Company issued 6,885,218 Units which separated upon closing and were issued separately as 6,885,218 shares of common stock and 3,019,242 warrants, each warrant exercisable for one share of common stock at an exercise price of $ 5.481 per share. The

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Company received aggregate gross proceeds from the Rights Offering of approximately $ 37,738 . The warrants issued in the Rights Offering meet the requirements for equity classification guidance in ASC 815-40.

The Company issued 570,000 warrants to the DOE in November 2025 to purchase shares of common stock at a price of $ 0.01 per share (the "DOE Warrants"). The DOE Warrants meet the requirements for equity classification guidance in ASC 815-40. The DOE Warrants are scheduled to expire November 21, 2030. There were 570,000 DOE Warrants outstanding as of June September 30, 2026 and December 31, 2025.

On August 3, 2026, the Company entered into a warrant agreement (the "Warrant Agreement") with Continental Stock Transfer & Trust Company governing the terms of certain warrants issued in connection with the FPUSA funding.

In consideration for the Initial Class A-2 Contribution, the Company issued, directly or indirectly, to CCM Frontier 20,017,772 warrants (the "CCM Warrants"). In consideration for the Initial Class C Contribution, the Company issued, directly or indirectly, to HBC 10,008,886 warrants (the "HBC Warrants" and, together with the CCM Warrants, the "HBC & CCM Warrants"). Each HBC & CCM Warrant is exercisable for one share of the Company's common stock at an exercise price of $ 5.481 per share.

The HBC & CCM Warrants became exercisable upon issuance and remain exercisable until the tenth anniversary of the issuance date, unless earlier exercised or redeemed in accordance with their terms. The HBC & CCM Warrants may be exercised for cash or on a cashless basis, subject to the provisions of the Warrant Agreement.

The holders of the HBC & CCM Warrants do not possess the rights of a stockholder, including voting rights, with respect to the shares underlying the HBC & CCM Warrants until such HBC & CCM Warrants are exercised and shares of common stock are issued. Following exercise, the holders are entitled to the rights of stockholders with respect to the shares issued upon exercise.

The HBC & CCM Warrants meet the requirements for equity classification guidance in ASC 815-40.

The Company recorded treasury stock of $ 0 1,188 and $ 488 2,269 for the three and six nine months ended June September 30, 2025, 2026, respectively, for shares withheld from employees to cover the options exercise costs and payroll tax liability of RSUs vested. liabilities. The treasury stock was immediately retired.

The Company recorded treasury stock of $ 0 and $ 488 for the three and nine months ended September 30, 2025, respectively, for shares withheld from employees to cover the payroll tax liability of RSUs vested. The treasury stock was immediately retired.

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Each Series B Preferred Stock has a par value of $ 0.0001 per share. The table below summarizes the Company's outstanding Series B Preferred Stock as of June September 30, 2026 and December 31, 2025.

EOS ENERGY ENTERPRISES, INC.

NOTES TO THE UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (In thousands, except share and per share amounts)

19. Redeemable Preferred Stock (cont.)

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Series B-1 Preferred Stock 9/12/2024 31.940063 $ 841,999.99 31.940063 31,940,063 36,067,246

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Conversion rights: The Series B-1, B-2 and B-3 Preferred Stock is convertible into common stock at a conversion ratio of 1,129,217 shares of common stock per share of Series B Preferred Stock, and the Series B-4 Preferred Stock Preferred Stock is convertible into common stock at a conversion ratio of 1.0 million 1,213,276 shares of common stock per share of Series B Preferred Stock ("Conversion Ratio"). The Conversion Ratio is subject to antidilution protection that is triggered if the Company issues equity for a price per share that is less than the conversion price then in effect, subject to certain exceptions.

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During the third quarter of 2026, the Registered Direct Offering, Rights Offering, issuance of warrants and related exchange arrangements triggered anti-dilution adjustments to the conversion ratio of the Company's Series B-1, B-2, B-3 and B-4 Preferred Stock, under the terms of the Securities Purchase Agreement. As a result, the number of common shares issuable upon conversion increased by 4,127,183 , 3,722,271 , 4,943,806 and 2,289,962 shares for the Series B-1, B-2, B-3 and B-4 Preferred Stock, respectively resulting in the number of common shares issuable upon conversion of the Series B-1, B-2, B-3 and B-4 to be 36,067,246 , 32,528,734 , 43,203,670 and 19,595,032 , respectively. The Company recorded aggregate down-round deemed dividends of approximately $ 13,802 increasing Additional paid-in capital and Accumulated deficit on the Consolidated Statements of Shareholders' Deficit.

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Preemptive rights: The Series B Certificates of Designation contain customary preemptive rights that permit the Holders of Series B Preferred Stock to participate in certain future equity offerings by the Company.

Rights to distributions upon liquidation of the Company: In the event of a voluntary or involuntary liquidation, dissolution, or winding up of the Company, the holders of the Series B Preferred Stock are entitled to receive

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Preemptive rights: The Series B Certificates of Designation contain customary preemptive rights that permit the Holders of Series B Preferred Stock to participate in certain future equity offerings by the Company.

Rights to distributions upon liquidation of the Company: In the event of a voluntary or involuntary liquidation, dissolution, or winding up of the Company, the holders of the Series B Preferred Stock are entitled to receive distribution of any of the assets or surplus funds of the Company pro rata with the holders of the common stock and any other holders of the preferred stock of the Company issued pursuant to the SPA and the Credit Agreement (the "Investor Preferred Stock"), including the Series B Preferred Stock, in an amount equal to such amount per share as would have been payable had all shares of Series B Preferred Stock been converted to common stock.

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As of June September 30, 2026 and December 31, 2025, all then outstanding then-outstanding shares of Series B Preferred Stock were classified as mezzanine equity on the Unaudited Consolidated Balance Sheets at its redemption value because it is probable of becoming redeemable. The Company recorded remeasurement of the Series B Preferred Stock, which reduces Additional paid-in capital, on the Unaudited Consolidated Statements of Shareholders' Deficit.

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The following table provides the numerators and denominators used in computing basic and diluted net income (loss) per share for the three months ended June September 30, 2026 and 2025. Generally, basic earnings per share ("EPS") is computed by dividing earnings available to common shareholders by the weighted average number of shares of common stock outstanding during the period. In accordance with ASC 260, the DOE Warrants are included in basic EPS as the shares are issuable for little cash consideration. The SPA Warrant, Series B Preferred Stock, the warrants issued in 2023, May 2025 Convertible Notes and November 2025 Convertible Notes are participating securities that do not have the obligation to share in the losses of the Company. Therefore, the more dilutive of the "if-converted" and "two-class" method must be applied when calculating EPS for the common shares.

For purposes of basic EPS, the "two-class" method was applied and undistributed earnings were allocated to participating securities. These undistributed earnings were allocated based on each participating securities' proportionate share of the total weighted-average shares outstanding. On July 21, 2026, the Company completed its Rights Offering as described within Note 18, Shareholders' Deficit . As the exercise price of the right was less than the fair value of the Common stock, the right contained a bonus element. In accordance with ASC 260 — Earnings per Share , the Company's weighted average shares outstanding for basic and diluted loss per share were retroactively adjusted for all prior periods presented by a factor of 1.0045 .

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Three Months Ended June 30, Six Months Ended June 30,

Net (loss) income available $ ( 406,268 ) $ ( 248,778 ) $ 881,493 $ ( 153,645 )

September 30, Nine Months Ended

Net Income (Loss) available $ 360,717 $ ( 1,332,487 ) $ 1,242,210 $ ( 1,486,133 )

Less: Undistributed earnings allocated to participating securities ( 128,147 ) — 315,328 ( 443,291 ) —

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Weighted average shares outstanding - basic 339,799,132 237,741,328 339,920,441 231,616,540

Basic $ ( 1.20 ) $ ( 1.05 ) $ 1.67 $ ( 0.66 )

Weighted average shares outstanding - basic 361,795,384 272,839,188 347,292,217 246,192,674

Basic $ 0.64 $ ( 4.88 ) $ 2.30 $ ( 6.04 )

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Three Months Ended June 30, Six Months Ended June 30,

Net (loss) income available $ ( 406,268 ) $ ( 248,778 ) $ 881,493 $ ( 153,645 )

September 30, Nine Months Ended

Net Income (Loss) available $ 360,717 $ ( 1,332,487 ) $ 1,242,210 $ ( 1,486,133 )

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Adjustment for change in fair value on April, May and December 2023 Warrants ( 77,746 ) — ( 234,379 ) —

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Adjustment for change in fair value of HBC Exchange Right/CCM Call Option ( 11,270 ) — ( 11,270 ) —

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Dilutive effect of HBC Exchange Right/ CCM Call Option

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Six Months Ended June 30, 2026

Management has elected to recognize changes in the redemption value of the Series B Preferred Stock. At each balance sheet date, the redemption value of the Series B Preferred Stock will be calculated and remeasured to its redemption value. The remeasurement is recorded as a deemed dividend or contribution, which, in the absence of Retained earnings, is recognized within additional paid in capital and earnings available to common shareholders in computing basic and diluted EPS. Other potentially dilutive common shares and the related impact to earnings are considered when calculating EPS on a diluted basis.

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and 66 more changes in the filing

MD&A 166 changes

The following discussion should be read in conjunction with the accompanying Unaudited Condensed Consolidated Financial Statements for the six nine months ended June September 30, 2026 and 2025 and the Company's Annual Report on Form 10-K for the year ended December 31, 2025, including the financial statements and notes thereto.

The Company offers an innovative Znyth™ technology battery energy storage system ("BESS") designed to provide the operating flexibility to manage increased grid complexity and price volatility resulting from an overall increase in renewable energy generation and a congested grid coming from an increase in electricity demand growth. The Company's BESS is a validated chemistry with accessible non-precious earth components in a durable design that is intended to deliver results in even the most extreme temperatures and conditions. The system is designed to be safe, flexible, scalable, sustainable and manufactured in the United States, using raw materials primarily sourced in the United States. We believe the Company's Z3 battery module is the core of its innovative systems. The Z3 battery module is the only U.S. designed and manufactured battery module that today provide utilities, independent power producers, renewables developers and C&I customers with an alternative to lithium-ion and lead-acid monopolar batteries for critical 3- to 12-hour discharge duration applications. We believe the Z3 battery will transform how utility, industrial and commercial customers store power.

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The Company's growth strategy contemplates increasing sales of battery energy storage systems and related software and services through a direct sales team and sales channel partners. The Company's current and target customers include utilities, project developers, independent power producers, and C&I companies and government contracts.

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In 2025, the Company introduced DawnOS, a software platform designed to enhance the value, reliability and safety of the Company's BESS. DawnOS builds upon the Z3 battery architecture through a fully integrated hardware and software solution. It serves as the system's intelligence layer and is designed to manage large numbers of battery modules in real time. The platform provides precise balancing, dynamic switching and continuous system operation, including in situations where individual modules within a string become imbalanced. DawnOS is intended to increase usable energy per cycle, reduce field service requirements and operate with embedded security and automation features. Through its advanced control capabilities, the Company expects DawnOS to be an integral component of its product portfolio going forward, reflecting its role in improving system resilience, efficiency and overall operational performance.

The Company has successfully transitioned to the Eos Z3 platform, enabled by the commissioning and commercial operation of its first fully automated battery manufacturing line. The Z3 leverages Building on the same proven underlying chemistry which that has demonstrated durability over more than 3 million cycles, while incorporating the Z3 incorporates a redesigned mechanical architecture that enhances performance, reduces costs and improves manufacturability. Since commencing shipments of Z3 battery modules have been shipped since in the third quarter of 2023, and the transition reflects over Company has continued to leverage more than fifteen years of accumulated insights and operational experience The Company believes this experience will continue to drive manufacturing efficiencies as production scales and its state-of-the-art operations expand. In 2025, the Company further enhanced its product offering with the introduction of DawnOS, a software platform that serves as the intelligence layer of its battery energy storage system ("BESS"). Fully integrated with the Z3 architecture, DawnOS is designed to manage large numbers of battery modules in real time through advanced balancing, dynamic switching, automation and embedded security capabilities. The platform is intended to increase usable energy per cycle, improve system reliability and resilience, reduce field service requirements and enable continuous operation even when individual modules become imbalanced. The Company expects DawnOS to be an integral component of its product portfolio going forward, supporting enhanced efficiency, safety and overall system performance.

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Frontier Power USA Parent, LLC ("FPUSA")

In May 2026 and June 30, 2026, the Company announced the planned formation of FPUSA, a joint venture with CCM Frontier and HBC. FPUSA is an independent development and investment company established to build, own and operate a diversified portfolio of long-duration battery energy storage projects with the strategy of becoming an Independent Power Producer ("IPP").

FPUSA is expected to enhance the Company's ability to convert its existing commercial pipeline into booked orders and then energy storage systems operating in the field by providing an integrated financing solution to support multiple financing pathways for project deployment. These include sponsor equity contributions from Eos, CCM Frontier and HBC, potential institutional debt financings structured to target investment-grade characteristics supported by the Technology Performance Insurance ("TPI") framework, and project-level debt facilities provided by commercial bank lenders. Management believes that the inclusion of TPI may broaden access to capital which is designed to support lender confidence in system performance. Management believes this structure will reduce execution friction for customers and counterparties and support the acceleration and expansion of the Company's energy storage systems operating in the field.

Governance of Eos's equity interests in FPUSA will be conducted through an independent investment committee, and transactions between the Company and FPUSA are expected to be conducted on arm's-length commercial terms. FPUSA is targeting the development of a multi-gigawatt-hour pipeline of long-duration energy storage projects across data center, utility and industrial end markets, which is expected to further support the growth and visibility of the Company's revenue profile over time.

In connection with these arrangements, Cerberus has agreed to extend the lock-up period on its existing Eos holdings through December 21, 2026.

In May 2026, in connection with the planned formation of FPUSA, the Company announced a rights offering (the "Rights Offering") targeting approximately $150.0 million. In the Rights Offering, shareholders of Eos common stock and holders of its warrants to purchase common stock issued on April 14, 2023, May 17, 2023, December 19, 2023, and November 21, 2025 as of the record date of 5:00pm New York time on July 1, 2026 (collectively, "Eligible Holders"), would receive rights to acquire a certain number of units, comprised of the Company's common stock and warrants (the "Units") in a rights offering to fund the Company's previously announced capital contribution in the FPUSA joint venture.

On June 30, 2026, the Company announced updated terms for the rights offering such that each right was expected to entitle an Eligible Holder the right to purchase approximately 0.071193 of a Unit at a subscription price equal to $5.481 per whole Unit, an approximate 10% discount to the closing price of the Company's common stock on June 29, 2026. Each Unit would consist of one share of Eos common stock and 0.4388 of a warrant, with each whole warrant entitling the holder to purchase one share of Eos common stock at an exercise price of $5.481 per share, subject to adjustment. The warrants are expected to expire on the 10 year anniversary of the closing of the rights offering.

The Company elected to conduct the rights offering to ensure that all stockholders of record as of July 1, 2026 had the opportunity to participate in the equity financing on a pro rata basis. This structure enabled existing stockholders to participate alongside the Company's largest investors in the capitalization of FPUSA.

Registered Direct Offering

On June 30, 2026, the Company announced the pricing of a registered direct offering pursuant to which it intended to issue 13,683,634 of common stock and 6,004,378 warrants, each warrant exercisable for one share of common stock at an exercise price of $5.481 per share, to HBMF. The Company received aggregate gross proceeds from the registered direct offering of approximately $75.0 million.

Thorn Hill Expansion

In June 2026, the Company successfully launched commercial production at its Thorn Hill manufacturing facility in Marshall Township, Pennsylvania, following successful site acceptance testing for its second Z3 manufacturing line. This milestone reinforces execution confidence by demonstrating a proven, repeatable and scalable production model. The expansion enhances operational flexibility and supports growing customer demand with the fortification of the Company's manufacturing foundation for future growth.

Strategic Energy Management System ("EMS") Collaboration with WATTMORE, Inc.

In August 2026, the Company entered into a non-exclusive strategic collaboration agreement with WATTMORE, Inc. to integrate WATTMORE's Intellect Operate energy management and power plant control platform with the Company's Z3 long-duration energy storage systems and DawnOS software. Under the agreement, Eos will deploy WATTMORE's platform on select customer projects, expanding the controls ecosystem for the Company's energy storage solutions and supporting streamlined project deployment.

Management believes the integrated platform will simplify project deployment, reduce implementation complexity and enhance the overall customer value proposition by offering a more comprehensive energy storage solution.

Manufacturing Consolidation

In August 2026, the Company announced plans to consolidate its battery manufacturing operations at its Thorn Hill facility in Warrendale, Pennsylvania. Commercial production at the 432,000-square-foot facility commenced in June 2026, and our battery manufacturing activities have now been centralized into a single location. Both the Thorn Hill and Turtle Creek facilities will continue to support cube assembly, testing, and shipping operations.

The Thorn Hill facility is expected to provide approximately 4 GWh of annual nameplate manufacturing capacity when both production lines are fully operational, supporting the Company's anticipated growth and expansion of customer deployments.

This consolidation represents a key component of the Company's ongoing efforts to enhance manufacturing scalability and become profitable. Management believes the consolidation will improve manufacturing efficiency by reducing material handling and streamlining production workflows. Upon completion of the transition, the Company expects to achieve conversion cost reductions, with benefits anticipated to begin in 2027. The Company currently expects to complete the transition without impacting customer delivery commitments.

In September 2026, the Company. received an $87.0 million advance under the DOE Loan Facility, bringing total borrowings under the facility to approximately $178.0 million. The advance reimbursed 80% of eligible costs associated with the Company's Thorn Hill manufacturing facility and supports the ramp-up of its second manufacturing line, which has a designed annual capacity of approximately 2 GWh.

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Three Months Ended June 30, Six Months Ended June 30,

($ in thousands) 2026

Three Months Ended September 30, Nine Months Ended September 30, ($ in thousands) 2026

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Revenue $ 13,741 $ 15,236 $ (1,495) (10) % $ 70,704 $ 25,693 $ 45,011 175 %

Revenue - related party 55,034 — $ 55,034 100 % 55,034 — $ 55,034 100 %

Total revenue $ 68,775 $ 15,236 $ 53,539 351 % $ 125,738 $ 25,693 $ 100,045 389 %

Revenue $ 14,284 $ 30,512 $ (16,228) (53) % $ 84,988 $ 56,205 $ 28,783 51 %

Revenue - related party 68,447 — $ 68,447 — % 123,481 — $ 123,481 — %

Total revenue $ 82,731 $ 30,512 $ 52,219 171 % $ 208,469 $ 56,205 $ 152,264 271 %

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For the three months ended June 30, 2026, Total revenue increased by $53.5 million or 351% from $15.2 million. For the six months ended June 30, 2026, Total revenue increased by $100.0 million or 389% from $25.7 million. The increase for the three and six months ended June 30, 2026 was primarily driven by an increase in deliveries, an increase in the average selling price and higher revenue from third-party materials. These increases were partially offset by a decline in service revenue.

Three Months Ended June 30, Six Months Ended June 30,

($ in thousands) 2026

For the three months ended September 30, 2026, Total revenue increased by $52.2 million or 171% from $30.5 million. For the nine months ended September 30, 2026, Total revenue increased by $152.3 million or 271% from $56.2 million.

The increase for the three months ended September 30, 2026 was primarily driven by a 229% increase in deliveries, higher revenue from third-party materials and an increase in service revenue. The increase for the nine months ended September 30, 2026 was primarily driven by a 260% increase in deliveries, an increase in third-party materials and an increase in service revenue.

The Company's revenue profile is influenced by the timing of project deployments. As a result, revenue and customer concentration may fluctuate significantly between reporting periods, depending on shipment schedules and project execution milestones. For the three months ended September 30, 2026, approximately 83% of the Company's revenue was attributable to deliveries associated with related party projects. For the nine months ended September 30, 2026, approximately 59% of revenue attributable to deliveries associated with related-party projects.

The Company expects revenue concentration to vary from period to period as individual projects advance through their delivery schedules. We expect the Company's revenue mix to align generally with the composition of its backlog and the timing of project deliveries. Accordingly, revenue and customer concentration in any given reporting period may be influenced by the timing and scale of specific project deliveries rather than changes in underlying customer demand.

Three Months Ended September 30, Nine Months Ended September 30, ($ in thousands) 2026

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Cost of goods sold $ 117,576 $ 46,189 $ 71,387 155 % $ 218,966 $ 81,185 137,781 170 %

Cost of goods sold $ 126,934 $ 64,437 $ 62,497 97 % $ 345,900 $ 145,622 200,278 138 %

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For the three months ended June 30, 2026, Cost of goods sold increased by $71.4 million or 155% from $46.2 million recognized during the three months ended June 30, 2025. For the six months ended June 30, 2026, Cost of goods sold increased by $137.8 million or 170% from $81.2 million recognized during the six months ended June 30, 2025 . The increase in Cost of goods sold for the three and six months ended June 30, 2026 was driven by costs associated with significantly higher cube deliveries, higher direct and indirect labor, higher field service costs associated with increased deliveries and higher volume-driven warranty accruals. These increases were partially offset by tax credit recognition.

Cost of goods sold for the three and six months ended June 30, 2026 reflected continued progress in reducing battery system manufacturing costs, driven by higher production efficiencies and increased output at the Turtle Creek facility. During the second quarter, the Company expanded its manufacturing capacity and commenced commercial production from its second battery line on June 16, 2026. Initial commercial production began during the quarter; however, labor and overhead absorption continued to be impacted by the Eos operating at partial production levels as the expanded facility ramps toward planned capacity. The Company expects utilization, fixed-cost absorption and manufacturing efficiencies to improve as production volumes increase.

In addition, field-related costs increased during the quarter as the Company's installed base continued to grow and as it advanced the deployment of DawnOS upgrades across legacy customer systems. These activities support long-term product performance and customer experience but increased service and support costs during the period.

Inventory balances also increased during the quarter to support higher production levels and anticipated customer deliveries. Consistent with the Company's negative gross profit position, the related inventory reserve increased during the period.

As the Company ramps production, the Company continues to see the benefit of the PTCs. For the six months ended June 30, 2026 and 2025, the Company recognized $22.8 million and $6.4 million, respectively, reduction of cost of goods sold related to the PTC.

For the three months ended September 30, 2026, Cost of goods sold increased $62.5 million or 97% compared to the three months ended September 30, 2025. For the nine months ended September 30, 2026, Cost of goods sold increased $200.3 million or 138% compared to the nine months ended September 30, 2025. The increase primarily relates to raw materials and outside labor as the Company continues to ramp production.

The increase in Cost of goods sold for the three and nine months ended September 30, 2026 was less than the growth of revenue allowing the Company to generate gross margin improvements. For the three months ended September 30, 2026, gross margin improved to approximately (53)% from (111)% from the three months ended September 30, 2025, an improvement of 58 percentage points. For the nine months ended September 30, 2026, gross margin improved to approximately (66)% from (159)% for the nine months ended September 30, 2025, an improvement of 93 percentage points. The Company is currently executing a fully deployed margin improvement program across the organization. For direct material, engineering and procurement are partnering in bundle buy negotiations, product redesign and supplier collaboration programs to deliver cheaper solutions. For conversion costs, the Company is beginning to realize savings from the more efficient lay out and automated process at Thorn Hill as volume is ramping. As the cost structure initiatives are implemented and operational efficiencies continue to improve, management expects further gross margin improvement in future periods.

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Three Months Ended June 30, Six Months Ended June 30,

($ in thousands) 2026

Three Months Ended September 30, Nine Months Ended September 30, ($ in thousands) 2026

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R&D expenses $ 10,505 $ 7,201 $ 3,304 46 % $ 21,224 $ 14,038 7,186 51 %

R&D expenses $ 10,910 $ 6,925 $ 3,985 58 % $ 32,134 $ 20,963 11,171 53 %

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For the three months ended June 30, 2026 Research and development expenses increased $3.3 million or 46%, compared to the three months ended June 30, 2025. For the six months ended June 30, 2026, Research and development expenses increased $7.2 million or 51% compared to the six months ended June 30, 2025. The increase for the three and six months ended June 30, 2026 was primarily attributable to higher facility costs, materials and supplies, outside services and payroll-related costs.

For the three months ended September 30, 2026 Research and development expenses increased $4.0 million or 58%, compared to the three months ended September 30, 2025. For the nine months ended September 30, 2026, Research and development expenses increased $11.2 million or 53% compared to the nine months ended September 30, 2025. The increase primarily relates to payroll, outside services and material costs.

The Company has continued to strategically invest in research and development initiatives designed to reduce production costs, improve product performance and further vertically integrate its battery solution. Key areas of investment include simplifying the Z3 battery design, qualifying alternative materials, increasing manufacturing efficiency and enhancing control systems to improve site monitoring capabilities, optimize system performance and improve automated system operation. From a cost category standpoint, the increase in R&D was primarily related to costs of material and supplies, outside services and payroll related costs.

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Three Months Ended June 30, Six Months Ended June 30,

($ in thousands) 2026

Three Months Ended September 30, Nine Months Ended September 30, ($ in thousands) 2026

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SG&A expenses $ 24,500 $ 25,488 $ (988) (4) % $ 48,595 $ 46,483 2,112 5 %

SG&A expenses $ 23,819 $ 19,786 $ 4,033 20 % $ 72,414 $ 66,269 6,145 9 %

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For the three months ended June 30, 2026 Selling, general and administrative expenses decreased $1.0 million or 4% compared to the three months ended June 30, 2025. The decrease for the three months ended June 30, 2026, was primarily attributable to a decrease in bad debt expense, stock compensation and outside services, partially offset by increases to facility costs, marketing and payroll related items.

For the six months ended June 30, 2026, Selling, general and administrative expenses increased $2.1 million or 5% compared to the six months ended June 30, 2025. The increase for the six months ended June 30, 2026 was primarily attributable to higher facility costs, marketing, outside services and payroll related items, partially offset by a decrease in bad debt expense and stock compensation.

For the three months ended September 30, 2026 Selling, general and administrative expenses increased $4.0 million or 20% compared to the three months ended September 30, 2025. For the nine months ended September 30, 2026, Selling, general and administrative expenses increased $6.1 million or 9% compared to the nine months ended September 30, 2025. The increases in SG&A was primarily related to an increase in payroll and outside services.

The Company has invested ahead of expected growth by building the team, systems and capabilities required to support a significantly larger revenue base. As revenue grows, management expects SG&A expenses to grow at a slower pace than revenue, allowing SG&A to become a smaller percentage of revenue over time. As a result, SG&A expenses as a percentage of revenue improved to approximately 29% for the three months ended September 30, 2026, compared to 65% for the same period in the prior year, representing a 36 percentage point improvement. For the nine months ended September 30, 2026, SG&A expenses improved to approximately 35% of revenue compared to 118% of revenue in the prior-year period, representing an 83 percentage point improvement.

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Three Months Ended June 30, Six Months Ended June 30,

($ in thousands) 2026

Three Months Ended June 30, Six Months Ended June 30,

Three Months Ended September 30, Nine Months Ended September 30, ($ in thousands) 2026

Loss from write-down of property, plant and equipment $ 5 108 $ 205 585 $ 76 184 $ 766 1,351

The Company incurred a loss of $0.2 million from write-down of property, plant and equipment For the three and nine months ended June September 30, 2025, and 2026, the Company incurred a loss of $0.1 million and $0.8 $0.2 million, for the six months ended June 30, 2026 and 2025, respectively, For the three from write-down of property, plant and six months ended June 30, 2026, the write-downs were mainly related to miscellaneous equipment. and tooling that could not be repurposed. In 2025, The write-downs were mainly due to design changes from the Z3-Phase 1 attributable to Z3-Phase 2 production in which the Phase 1 production assets could not be utilized or repurposed for Phase 2 production. Additionally, the loss from write-down of property, plant and equipment contains costs for disposal of miscellaneous equipment and tooling. that cannot be repurposed for more automated processes.

For the three and nine months ended September 30, 2025, the Company incurred a loss of $0.6 million and $1.4 million, respectively, from write-down of property, plant and equipment. The write-downs were mainly attributable to design changes from the Z3-Phase 1 to Z3-Phase 2 production in which the Phase 1 production assets could not be utilized or repurposed for

Phase 2 production. Additionally, the loss from write-down of property, plant and equipment contains costs for disposal of miscellaneous equipment and tooling that cannot be repurposed for more automated processes.

Restructuring expense

September 30, Nine Months Ended

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Interest expense $ (11,972) $ (2,980) $ (24,214) $ (3,958)

Restructuring expense $ 281 $ — $ 281 $ —

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and 86 more changes in the filing

Market risk 1 change

There have been no material changes in the Company's market risk exposures for the six nine months ended June September 30, 2026, as compared to those discussed in its Annual Report on Form 10-K for the year ended December 31, 2025.

Controls and procedures 2 changes

1 unchanged paragraph

Our management, with the participation and supervision of our Chief Executive Officer and our Chief Financial Officer, have has evaluated our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e)) under the Exchange Act as of the end of the period covered by this report. Based upon that evaluation and consistent with the evaluations previously reported in prior periods, the CEO and CFO have concluded that, as of the end of the period covered by this Report our disclosure controls and procedures were effective to provide reasonable assurance that information we are required to disclose in reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in SEC rules and forms, and that such information is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosure. Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives, and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

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There were no changes in our internal control over financial reporting during the quarter ended June September 30, 2026, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Risk factors 7 changes

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Risks Related to Our Investment in Frontier Power USA FPUSA

Our minority investment in Frontier Power USA FPUSA and related commercial arrangements may expose us to new risks and may not achieve the anticipated strategic or financial benefits.

Our minority investment in Frontier Power USA FPUSA represents an expansion of our business model beyond the manufacture and sale of energy storage systems. Frontier Power USA is expected FPUSA has been formed to develop, finance, own and operate long-duration energy storage projects, which may expose us to risks associated with project development, financing, permitting, construction, interconnection, operations, electricity markets, asset ownership, insurance availability and performance, third-party performance and other matters outside our historical business. These risks may be difficult to predict or manage and may be affected by factors outside our control. Because we do not own a controlling interest in Frontier Power USA, FPUSA, we may have limited ability to influence strategic, operational, financing or commercial decisions that could affect the value of our investment or our broader business objectives.

Frontier Power USA FPUSA is, and is expected to become remain, a customer of the Company under arm's length commercial arrangements, and may also finance or facilitate purchases of our products by project companies, developers and other third parties, either directly or as co-customers with FPUSA. Our future revenues, backlog, customer concentration and growth strategy may therefore be affected, in part, by Frontier Power USA's FPUSA's ability to develop, finance, and construct, own, operate and monetize energy storage projects. If Frontier Power USA FPUSA is unable to execute its business plan, experiences financial or operational challenges, reduces or delays purchases of our products, or otherwise fails to meet expectations, our business, financial condition, results of operations and growth prospects could be adversely affected. Because FPUSA has represented, and may continue to represent, a significant portion of our backlog or revenues, any such reduction or delay could have a disproportionate effect on our near-term commercial performance. We will also need to continue to maintain a diversified customer base and avoid undue reliance on any single customer or commercial relationship.

As currently constructed, Frontier Power USA will be FPUSA is controlled and managed by affiliates of Cerberus Capital Management, a related party with other financing and equity relationships with the Company. As a result, situations may arise in which the interests of Frontier Power USA, FPUSA, its owners and the Company are not fully aligned with respect to commercial arrangements, governance matters, financing decisions or other business activities. While Although we have governance rights and expect to work collaboratively with our partners, and maintain appropriate governance arrangements, our ability to influence matters affecting Frontier Power USA FPUSA may be limited and may depend on the nature of our ownership and governance rights from time to time.

At this time, the Company has concluded that Frontier Power USA FPUSA is not required to be consolidated into our financial statements based on the facts and circumstances currently known to us. This conclusion involves some judgment and will be reassessed periodically, including at the conclusion of each reporting period and as relevant facts and circumstances evolve. Changes in Frontier Power USA's FPUSA's business, ownership structure, governance arrangements, financing activities or other factors could result in a different accounting conclusion in the future, which could materially affect our financial statements, reported operating results and financial condition.

Our investment in Frontier Power USA FPUSA may be difficult to monetize and may result in losses, impairment charges, dilution or other adverse consequences. Our ability to exit or monetize our investment may be limited. In addition, equity financings, warrants, exchange rights or other securities issued or issuable in connection with our investment or related transactions have diluted and may further dilute existing stockholders. If our investment does not perform as expected, or fails to produce the anticipated strategic, operational or financial benefits expected, if the value of our investment declines, or if related obligations exceed our expectations, our business, financial condition, results of operations, liquidity and stockholder value could be materially adversely affected.

Other information 31 changes

On July 15, 2026 , Joseph Mastrangelo , Chief Executive Officer , adopted a new Rule 10b5-1 trading plan . This plan will terminate on September 30, 2027 and provides for the sale of a predetermined percentage the Section 16 officer's restricted stock unit award vesting, sufficient to cover the tax liability for the Section 16 officer.

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Form 8-K File No. 001-39291 3.1 May 19, 2022

3.4* Second Third Amended and Restated Bylaws of the Company

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10.1 Employment Agreement between Eos Energy Enterprises, Inc. and Alessandro Lagi

10.2* Limited Consent to Loan Guarantee Agreement, dated April 1, 2026, by and between Eos Energy Enterprises, Inc. and the United States Department of Energy

10.3* Limited Consent and Waiver to Loan Guarantee Agreement, dated June 26, 2026, by and between Eos Energy Enterprises, Inc. and the United States Department of Energy

10.4* Limited Consent and Waiver to Loan Guarantee Agreement, dated June 29, 2026 by and between Eos Energy Enterprises, Inc. and the United States Department of Energy

4.3 Warrant Agreement, dated August 3, 2026, by and between the Registrant and Continental Stock Transfer & Trust Company

Form 8-K File No. 001-39291 10.1 April 30, 4.2 August 6, 2026

4.4 Exchange Agreement, dated August 4, 2026, by and between the Registrant and HBC MSF Capital Solutions Blocker II LLC

Form 8-K File No. 001-39291 4.3 August 6, 2026

4.5 Registration Rights Agreement dated August 4, 2026 by and between Eos Energy Enterprises, Inc. and CCM Frontier JV Holdco, LLC

Form 8-K File No. 001-39291 4.4 August 6, 2026

4.6 Registration Rights Agreement dated August 4, 2026 by and between Eos Energy Enterprises, Inc. and HBC MSF Capital Solutions Blocker II LLC

Form 8-K File No. 001-39291 4.5 August 6, 2026

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10.1 Amended and Restated Limited Liability Company Agreement dated August 4, 2026 by and among Eos Energy Enterprises, Inc., CCM Frontier JV Holdco, LLC and HBC MSF Capital Solutions Blocker II LLC

Form 8-K File No. 001-39291 10.1 August 6, 2026

10.5* Third Amendment to Loan Guarantee 10.2 Contribution and Warrants Issuance Agreement dated August 4, 2026 by and between Eos Energy Enterprises, Inc. and the United States Department of Energy Frontier Power USA Parent, LLC

Form 8-K File No. 001-39291 10.2 August 6, 2026

10.3 Side Letter dated August 4, 2026 by and between Eos Energy Enterprises, Inc., CCM Frontier JV Holdco, LLC, and Frontier Power USA Parent, LLC

Form 8-K File No. 001-39291 10.3 August 6, 2026

10.4 Third Amendment to Loan Guarantee Agreement, dated August 4, 2026, by and between Eos Energy Enterprises, Inc. and the United States Department of Energy

Form 8-K File No. 001-39291 10.4 August 6, 2026

10.5* Separation Agreement, dated September 10, 2026, by and between Eos Energy Enterprises, Inc. and Nathan Kroeker

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Incorporated by Reference

Exhibit Number Description of Document Schedule/Form File Number Exhibits Filing Date

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** Furnished herewith.

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Date: August 5, 2026

Date: November 5, 2026

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Date: August 5, 2026

Date: November 5, 2026

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