Management Change/Compensation (Form 8-K)

On December 23, 2025, Stephen G. Machatha, Ph.D. notified Aldeyra Therapeutics, Inc. (the "Company") of his decision to voluntarily resign from his position as Chief Development Officer of the Company to pursue other professional opportunities. Dr. Machatha's last day of employment with the Company will be on or before March 31, 2026 (such actual last day of employment with the Company, the "Separation Date").

In connection with the foregoing, on December 23, 2025, the Company and Dr. Machatha entered into a Transition Agreement (the "Transition Agreement"). Subject to the terms and conditions of the Transition Agreement, Dr. Machatha will continue to be employed by the Company through the Separation Date (the "Transition Period") to help ensure a smooth transition of his duties and institutional knowledge. During the Transition Period, Dr. Machatha will continue to receive his current base salary and be eligible to participate in applicable employee benefit plans. Any outstanding options to purchase shares of the Company's common stock or restricted stock units previously granted to Dr. Machatha will continue to vest during the Transition Period in accordance with their terms. In addition, in exchange for his execution of the Transition Agreement, Dr. Machatha will be entitled to a lump sum payment of $88,000, representing 50% of his potential 2025 bonus based on 110% of his target bonus. The Transition Agreement also includes customary provisions regarding non-disparagementand release of claims. If Dr. Machatha executes an additional release of claims between the Separation Date and the business day following the Separation Date, the Company will pay Dr. Machatha a lump sum payment of $88,000, representing the remaining 50% of his potential 2025 bonus based on 110% of his target bonus. Except as expressly modified by the Transition Agreement, the Offer Letter between Dr. Machatha and the Company dated October 21, 2015, as amended, will remain in full force and effect in accordance with its terms until the Separation Date.

Dr. Machatha's decision to resign was not due to a dispute or disagreement with the Company or its management regarding any matter relating to the Company's operations, policies, or practices, including with respect to any matters relating to the Company's accounting practices or financial reporting.

The foregoing description of the Transition Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Transition Agreement, a copy of which will be filed with the Company's Annual Report on Form 10-Kand incorporated by reference herein.