Acadia Healthcare Company, Inc.

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (See General Instruction A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

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Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition.

On July 28, 2026, Acadia Healthcare Company, Inc. (the “Company”) issued a press release announcing, among other things, the Company’s operating and financial results for the second quarter ended June 30, 2026. The press release is furnished herewith as Exhibit 99.1 hereto and is incorporated herein by reference.

Item 7.01. Regulation FD Disclosure.

The Company will conduct a conference call to discuss its second quarter 2026 financial results on Wednesday, July 29, 2026 at 9:00 a.m. Eastern Time. In discussing the Company’s results, Company representatives may refer to information described on the slides furnished with this Current Report on Form 8-K as Exhibit 99.2 hereto. The live broadcast of the conference call and the slides will be available on the Company’s website, www.acadiahealthcare.com, by clicking on the “Investors” link. The webcast of the conference call will be available on the Company’s website for thirty days.

The information furnished pursuant to Item 2.02 and Item 7.01 of this Current Report on Form 8-K, including the information in Exhibit 99.1 and Exhibit 99.2 hereto, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.