SUMMARY NOTICE OF PROPOSED SETTLEMENT

TO: ALL RECORD OR BENEFICIAL OWNERS OF THE COMMON STOCK OF ACADIA HEALTHCARE COMPANY, INC. ("ACADIA" OR THE "COMPANY") AS OF JULY 31, 2026.

YOU ARE HEREBY NOTIFIED, pursuant to an Order of the U.S. District Court for the Middle District of Tennessee (the "Court"), that a proposed Settlement has been reached between the parties to the above-captioned shareholder derivative action (the "Federal Derivative Action") and the shareholder derivative actions before the Court of Chancery of the State of Delaware captioned Pfenning v. Jacobs, et al., C.A. No. 2020-0915-NAC (Del. Ch.) (the "Pfenning Action")and Solak v. Jacobs, et al., C.A. 2021-0163-NAC (Del. Ch.) (the "Solak Action") (together with the Federal Derivative Action and the Pfenning Action, the "Derivative Actions"), brought on behalf of Acadia, which would resolve the Derivative Actions.

The Derivative Actions are brought by Robert Davydov (the "Plaintiff Davydov"), Margaret Pfenning ("Plaintiff Pfenning"), and John Solak ("Plaintiff Solak") (collectively with Plaintiff Davydov and Plaintiff Pfenning, "Plaintiffs") solely on behalf of and for the benefit of Acadia and against the Individual Defendants.1 Plaintiffs allege, among other things, that the Individual Defendants breached their fiduciary duties, wasted corporate assets, and were unjustly enriched by and through the alleged oversight failure in allowing the Company to make alleged misrepresentations regarding the Company’s compliance with applicable laws, patient care and staffing at the facilities, and the performance of the Company’s United Kingdom operations.

On December 10, 2026, at 1:30 p.m., the Court will hold the Settlement Hearing at the U.S. District Court for the Middle District of Tennessee, Nashville Division, located at the Fred D. Thompson U.S. Courthouse and Federal Building, 719 Church Street, Courtroom 6B, Nashville, TN 37203, to determine: (i) whether the terms of the Settlement are fair, reasonable, and adequate and should be approved; (ii) whether a final judgment should be entered; (iii) whether the Court should approve the agreed upon attorneys’ fees and reimbursement of expenses of $4,750,000 based on the monetary and corporate governance benefits conferred upon Acadia by the Settlement and any requested service awards to be paid therefrom to the Plaintiffs; and (iv) such other actions as may be necessary or proper under the circumstances.

The Settlement Hearing may be continued or adjourned by the Court without further notice to Current Acadia Stockholders. The Court may conduct the Settlement Hearing remotely without further notice to Current Acadia Stockholders.