Arq, Inc.

Rule 10b5-1 and non-Rule 10b5-1 Trading Arrangements

During the three months ended December 31, 2025, 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.

Second Loan Modification Agreement

On March 5, 2026, certain subsidiaries of the Company, including Corbin Project LLC, Arq Projects Holding Company LLC, Arq Corbin LLC and Arq Corbin Land LLC, each a Delaware limited liability company (collectively, “Borrowers”) and Community Trust Bank, Inc., a Kentucky corporation (“CTB”) entered into the second loan modification agreement (the "Second Loan Modification Agreement") to the Loan Agreement (USDA Guaranteed Loan) by and among CTB and the Borrowers dated January 27, 2021, as amended by that certain letter agreement dated January 21, 2022, that certain Loan Modification Agreement dated June 2, 2023 and as otherwise amended, modified and/or extended by the parties from time to time (collectively, the "Loan Agreement").

Pursuant to the terms of the Second Loan Modification Agreement, CTB agreed to (a) waive the Borrowers' obligation to satisfy certain financial covenants for the fiscal year ended December 31, 2025, and (b) suspend financial covenant testing for the fiscal year ending December 31, 2026.

As a condition to CTB's entry into the Second Loan Modification Agreement, the Borrowers agreed to deposit an additional $752,500 into the Interest Reserve Account, as defined in and established by the Loan Agreement. The Borrowers may withdraw from the Interest Reserve Account down to the Required Minimum Balance, as defined in the Second Loan Modification Agreement.

The foregoing description of the Second Loan Modification Agreement is only a summary of its material terms and does not purport to be complete and is qualified in its entirety by reference to the full text of the Second Loan Modification Agreement, which is filed as Exhibit 10.24 to this Annual Report on Form 10-K and incorporated herein by reference.

Departure of Chief Operating Officer and Chief Financial Officer

On March 4, 2026, the Company eliminated the role of Chief Operating Officer. Jeremy “Deke” Williamson will cease serving in that role, effective immediately. Mr. Williamson will remain employed by the Company until April 18, 2026, after which his employment will terminate.

Additionally, Jay Voncannon, Chief Financial Officer and principal financial officer of the Company, will cease serving in these roles, effective immediately. Mr. Voncannon will remain employed by the Company until April 18, 2026, after which date his employment will terminate.

The Company expects to enter into a separation agreement and release of claims with each of Messrs. Voncannon and Williamson, the terms of which will be disclosed once available.

Appointment of Principal Financial Officer

On March 4, 2026, the Board designated Stacia Hansen, the Company’s Chief Accounting Officer, Treasurer and principal accounting officer, as the Company’s principal financial officer, effective immediately.

The remaining information called for by Item 5.02(c) of Form 8-K has been previously reported and can be found in the Company’s definitive proxy statement and Current Report on Form 8-K, each filed with the Securities and Exchange Commission on April 21, 2025 and November 8, 2023, respectively, which information is incorporated by reference herein.