Energy Vault Holdings, Inc.

(a) Disclosure in lieu of reporting on a Current Report on Form 8-K.

Item 1.01 Entry into a Material Definitive Agreement

On May 18, 2026, the Company entered into a Securities Purchase Agreement (the “Purchase Agreement”) with YA II PN, Ltd. (the “Investor”), pursuant to which the Company agreed to issue senior secured convertible debentures (the “Senior Secured Convertible Debentures”) in multiple tranches with an aggregate principal amount of up to $75.0 million.

The initial tranche of $42.0 million will be funded at closing and net proceeds are expected to be $39.6 million after deductions for an original issue discount and origination fees. The Senior Secured Convertible Debentures are secured by assets of the Company, Energy Vault, Inc. and the Company’s Swiss and Australian subsidiaries.

The Senior Secured Convertible Debentures were issued at 95% of par, bear interest at 7.5% per annum (18.0% upon an uncured event of default), and mature on May 17, 2027. Beginning on September 18, 2026 and monthly thereafter (each, a “Payment Date”), approximate scheduled installments of principal and accrued interest are due as follows (per $10.0 million of original principal): $1.2 million on the first Payment Date, $1.2 million on each of the next three Payment Dates, $1.1 million on each of the next four Payment Dates, and $1.1 million at maturity. For the initial tranche, the floor price is $1.19 per share.

For each installment, the Company may (i) pay cash, (ii), if certain conditions are satisfied, elect to allow the Investor to convert the unpaid installment at a price equal to 97% of the lowest daily VWAP during the four consecutive trading days immediately preceding the conversion date, or (iii) satisfy the installment through a combination of cash and conversion. Investor conversions are subject to a beneficial ownership limit of 4.99% of the Company’s common stock and to a limit of

19.99% of the Company’s outstanding common stock as of closing unless stockholder approval to exceed such cap is obtained in accordance with the rules and regulations of the NYSE (the “Exchange Cap”). Pursuant to the Exchange Cap, the Senior Secured Convertible Debentures are convertible for a maximum of 33,251,333 shares of common stock.

An “Amortization Event” includes, among other things, (i) the Company’s common stock trading below the Floor Price for 5 of 7 consecutive trading days, (ii) issuance of more than 99% of the shares available under the Exchange Cap without stockholder approval, or (iii) from any time after the six-month anniversary of the issuance of the Senior Secured Convertible Debentures, the Investor is unable to sell its shares pursuant to Rule 144. While an Amortization Event is in effect, the monthly installment must be paid in cash and the installment amount may increase to the greater of the scheduled amount and 20.0% of then-outstanding principal.

The Purchase Agreement includes customary covenants and restrictions, including a prohibition on certain variable-rate transactions while amounts may be or are outstanding, limitations on additional indebtedness and liens subject to agreed exceptions (including specified project-level indebtedness for subsidiaries such as Calistoga and Cross Trails and certain refinancings), and limitations on the Company’s use of equity lines without Investor consent. The Company’s obligations under the Senior Secured Convertible Debentures are guaranteed by Energy Vault, Inc., Energy Vault Pty Ltd and Energy Vault SA. The Investor agreed not to engage in short sales of the Company’s equity, but may sell shares corresponding to submitted conversions. Net proceeds are expected to be used to fund, directly or indirectly, general working capital, development, construction and/or investment in energy storage projects and general corporate and administrative expenses.

The Senior Secured Convertible Debentures and related definitive agreements are governed by New York law. The Senior Secured Convertible Debentures and the shares of Common Stock issuable upon conversion thereof have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), and were offered and sold in a private placement in reliance on Section 4(a)(2) of the Securities Act and/or Rule 506 of Regulation D thereunder. The Investor represented that it is an accredited investor.

In connection to the foregoing, also on May 18, 2026, the Company and Investor agreed with respect to that Securities Purchase Agreement, by and among the Company and Investor, dated as of September 22, 2025 (as amended, the “2025 SPA”) that, among other things, Investor waives compliance with certain of the covenants, agreements, obligations and restrictions imposed on the Company pursuant to Article 4 of the 2025 SPA.

The foregoing description of the Purchase Agreement and the forms of Senior Secured Convertible Debentures does not purport to be complete and is qualified in its entirety by reference to the full text of each such agreement, which are attached to this Quarterly Report on Form 10-Q as Exhibits 10.15, 4.1 and 4.2, respectively, and incorporated herein by reference.

Item 2.03 Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant.

The information contained in Item 1.01 with respect to the Senior Secured Convertible Debentures is incorporated herein by reference.

Item 3.02 Unregistered Sales of Equity Securities.

The disclosure set forth above in Item 1.01 relating to the issuance of any shares to be issued in connection with a conversion of the Senior Secured Convertible Debentures and relating to the issuance of the Senior Secured Convertible Debentures, is incorporated by reference herein in its entirety.

The issuance of the Senior Secured Convertible Debentures pursuant to the Purchase Agreement was made in reliance upon the exemption from registration contained in Section 4(a)(2) of the Securities Act. This Quarterly Report on Form 10-Q shall not constitute an offer to sell or the solicitation of any offer to buy the securities discussed herein, nor shall there be any offer, solicitation, or sale of the securities in any state in which such offer, solicitation, or sale would be unlawful prior to registration or qualification under the securities laws of any such state.

(b) Material changes to the procedures by which security holders may recommend nominees to the board of directors.

None.

(c) Insider trading arrangements and policies.

During the three months ended March 31, 2026, no director or officer of the Company adopted orterminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K.