Eos Energy Enterprises, Inc.

On November 24, 2025 (the “Closing Date”), Eos Energy Enterprises, Inc. (the “Company”) issued $600,000,000 aggregate principal amount of its 1.75% Convertible Senior Notes due 2031 (the “Notes”). The Notes were issued pursuant to, and are governed by, an indenture (the “Indenture”), dated as of the Closing Date, between the Company and Wilmington Trust, National Association, as trustee (the “Trustee”). Pursuant to the purchase agreement between the Company and the representatives of the initial purchasers of the Notes, the Company granted the initial purchasers an option to purchase, for settlement within a period of 13 days from, and including, the date the Notes are first issued, up to an additional $75,000,000 principal amount of Notes. On November 20, 2025, the initial purchasers exercised such option to purchase additional Notes in full.

The Notes will be the Company’s senior, unsecured obligations and will be (i) equal in right of payment with the Company’s existing and future senior, unsecured indebtedness (including the Company’s 6.75% Convertible Senior Notes due 2030 (the “Existing 2030 Convertible Notes”)); (ii) senior in right of payment to the Company’s existing and future indebtedness that is expressly subordinated to the Notes; (iii) effectively subordinated to the Company’s existing and future secured indebtedness, to the extent of the value of the collateral securing that indebtedness; and (iv) structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables, and (to the extent the Company is not a holder thereof) preferred equity, if any, of the Company’s subsidiaries.

The Notes will accrue interest at a rate of 1.75% per annum, payable semi-annually in arrears on June 1 and December 1 of each year, beginning on June 1, 2026. The Notes will mature on December 1, 2031, unless earlier repurchased, redeemed or converted. Before September 3, 2031, noteholders will have the right to convert their Notes only upon the occurrence of certain events. From and after September 3, 2031, noteholders may convert their Notes at any time at their election until the close of business on the second scheduled trading day immediately before the maturity date. The Company will settle conversions by paying or delivering, as applicable, cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company’s election, based on the applicable conversion rate(s). However, unless and until the Company increases the number of authorized shares of its common stock, or otherwise increases the number of shares of its common stock available to settle conversions of the Notes, and, in each case, reserves the required number of shares solely for issuance upon conversion of the Notes, the Company will settle all conversions entirely in cash. The initial conversion rate is 61.3704 shares of the Company’s common stock per $1,000 principal amount of Notes, which represents an initial conversion price of approximately $16.29 per share of the Company’s common stock. The conversion rate and conversion price will be subject to customary adjustments upon the occurrence of certain events. In addition, if certain corporate events that constitute a “Make-Whole Fundamental Change” (as defined in the Indenture) occur, then the conversion rate will, in certain circumstances, be increased for a specified period of time.

The Notes will be redeemable, in whole or in part (subject to certain limitations described below), at the Company’s option at any time, and from time to time, on or after December 5, 2028 and on or before the 41st scheduled trading day immediately before the maturity date, but only if certain liquidity conditions are satisfied and the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price on (i) each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice; and (ii) the trading day immediately before the date the Company sends such redemption notice. However, the Company may not redeem less than all of the outstanding Notes unless at least $75.0 million aggregate principal amount of Notes are outstanding and not called for redemption as of the time the Company sends the related redemption notice. The redemption price will be a cash amount equal to the principal amount of the Notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date. In addition, calling any Note for redemption will constitute a Make-Whole Fundamental Change with respect to that Note, in which case the conversion rate applicable to the conversion of that Note will be increased in certain circumstances if it is converted after it is called for redemption.

If certain corporate events that constitute a “Fundamental Change” (as defined in the Indenture) occur, then, subject to a limited exception for certain cash mergers, noteholders may require the Company to repurchase their Notes at a cash repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the fundamental change repurchase date. The definition of Fundamental Change includes certain business combination transactions involving the Company and certain de-listing events with respect to the Company’s common stock.

The Notes will have customary provisions relating to the occurrence of “Events of Default” (as defined in the Indenture), which include the following: (i) certain payment defaults on the Notes (which, in the case of a default in the payment of interest on the Notes, will be subject to a 30-day cure period); (ii) the Company’s failure to send certain notices under the Indenture within specified periods of time; (iii) a default in the Company’s obligation to convert a Note upon the exercise of the conversion right with respect thereto, if such default is not cured within three business days after its occurrence; (iv) the Company’s failure to comply with certain covenants in the Indenture relating to the Company’s ability to consolidate with or merge with or into, or sell, lease or otherwise transfer, in one transaction or a series of transactions, all or substantially all of the assets of the Company and its subsidiaries, taken as a whole, to another person; (v) a default by the Company in its other obligations or agreements under the Indenture or the Notes if such default is not cured or waived within 60 days after notice is given in accordance with the Indenture; (vi) certain defaults by the Company or any of its significant subsidiaries with respect to indebtedness for borrowed money of at least $100,000,000; (vii) the rendering of certain judgments against the Company or any of its significant subsidiaries for the payment of at least $50,000,000, where such judgments are not discharged or stayed within 60 days after the date on which the right to appeal has expired or on which all rights to appeal have been extinguished; and (viii) certain events of bankruptcy, insolvency and reorganization involving the Company or any of its significant subsidiaries.

If an Event of Default involving bankruptcy, insolvency or reorganization events with respect to the Company (and not solely with respect to a significant subsidiary of the Company) occurs, then the principal amount of, and all accrued and unpaid interest on, all of the Notes then outstanding will immediately become due and payable without any further action or notice by any person. If any other Event of Default occurs and is continuing, then, the Trustee, by notice to the Company, or noteholders of at least 25% of the aggregate principal amount of Notes then outstanding, by notice to the Company and the Trustee, may declare the principal amount of, and all accrued and unpaid interest on, all of the Notes then outstanding to become due and payable immediately. However, notwithstanding the foregoing, the Company may elect, at its option, that the sole remedy for an Event of Default relating to certain failures by the Company to comply with certain reporting covenants in the Indenture consists exclusively of the right of the noteholders to receive special interest on the Notes for up to 365 days at a specified rate per annum not exceeding 0.50% on the principal amount of the Notes.

The above description of the Indenture and the Notes is a summary and is not complete. A copy of the Indenture and the form of the certificate representing the Notes are filed as exhibits 4.1 and 4.2, respectively, to this Current Report on Form 8-K, and the above summary is qualified by reference to the terms of the Indenture and the Notes set forth in such exhibits.