Core Natural Resources Inc

Rule 10b5-1 Trading Plans

Our executive officers and directors may from time to time enter into plans or arrangements for the purchase or sale of our Common Stock that are intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. During the three months ended December 31, 2024, no director or officer of the Company adopted or terminated 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.

Mine Safety - Reporting of Combustion-Related Activity at Underground Mine

On January 13, 2025, isolated combustion-related activity was reported at the Leer South mine, located in Barbour County, West Virginia. The Company temporarily sealed the Leer South mine's active longwall panel in order to extinguish isolated combustion-related activity there. The Company resumed development work with continuous miners in February 2025, and, based on collaborative, ongoing discussions with regulatory authorities, currently expects to resume longwall mining in mid-2025. The re-entry process will be multi-phased, beginning with the construction of ventilation controls followed by the resumption of continuous miner development.

Amendment to the Performance Incentive Plan

On February 18, 2025, the Performance Incentive Plan was amended to change the name of the plan to the Core Natural Resources, Inc. Equity Plan and to assume the shares of Arch common stock, par value $0.01, that were available for grant under the Arch Resources, Inc. 2016 Omnibus Incentive Plan, as amended from time to time, immediately prior to the consummation of the Merger (such shares, after appropriate adjustment to reflect the Merger, the “Remaining Arch Plan Shares”) so that the Remaining Arch Plan Shares are available for issuance under the Performance Incentive Plan in accordance with, and subject to the terms and conditions of, the New York Stock Exchange Listed Company Manual (including Rule 303A.08 thereof).