UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Acadia Pharmaceuticals Inc.

(Exact name of Registrant as Specified in Its Charter)

(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:

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 5.02 Departure Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

As previously disclosed in our Current Report on Form 8-K filed with the Securities and Exchange Commission on May 1, 2026, on April 27, 2026, Elizabeth H.Z. Thompson, Ph.D., Executive Vice President, Head of Research and Development of Acadia Pharmaceuticals Inc. (the “Company”), informed the Company of her planned retirement from the Company for personal reasons. As of October 23, 2026, Dr. Thompson will no longer serve as an employee of the Company or function in her former role as Head of Research and Development. Also, effective October 23, 2026, Dr Thompson will be retained as a consultant by the Company and intends to provide limited consulting services to the Company through December 31, 2026. The Company is in the process of identifying Dr. Thompson’s replacement.

Forward-Looking Statements

This Current Report on Form 8-K (this “Current Report”) contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “will,” “intends” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. These forward-looking statements are based on the Company’s expectations and assumptions as of the date of this Current Report. Each of these forward-looking statements involves risks and uncertainties. Actual results may differ materially from these forward-looking statements. Forward-looking statements contained in this Current Report include, but are not limited to, statements regarding Dr. Thompson’s continued service to the Company as a consultant, the duration of those consulting services, and the Company’s search for a replacement Head of Research and Development. Many factors may cause differences between current expectations and actual results, including the potential for Dr. Thompson to determine not to serve as a consultant to the Company. Other factors that may cause actual results to differ from those expressed or implied in the forward-looking statements in this Current Report are discussed in the Company’s filings with the Securities and Exchange Commission, including its Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K. Except as required by law, the Company assumes no obligation to update any forward-looking statements contained herein to reflect any change in expectations, even as new information becomes available.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.