Material Event (Form 8-K)

As previously announced, on May 6, 2026, Catalyst Pharmaceuticals, Inc. ("Catalyst") entered into an Agreement and Plan of Merger (the "Merger Agreement") with Angelini Pharma S.p.A., an Italian Società per azioni ("Angelini Pharma"), and Angelini Cielo Inc., a Delaware corporation and wholly-owned subsidiary of Angelini Pharma ("Merger Sub"), providing for the merger of Merger Sub with and into Catalyst (the "Merger"), with Catalyst surviving the Merger as a wholly-owned subsidiary of Angelini Pharma.

The closing of the Merger and the other transactions contemplated by the Merger Agreement (together with the Merger, the "Transactions") is subject to customary closing conditions, including, among others, the expiration or termination of any applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the "HSR Act").

On May 20, 2026, Catalyst and Angelini Pharma each filed a Premerger Notification and Report Form under the HSR Act with the Antitrust Division of the U.S. Department of Justice and the U.S Federal Trade Commission (the "FTC") in connection with the Transactions. On June 22, 2026, Catalyst became aware that on June 16, 2026, the FTC had granted early termination of the waiting period under the HSR Act.

The closing of the Transactions remains subject to the satisfaction or waiver of other customary closing conditions, including adoption of the Merger Agreement by holders of at least a majority of the outstanding shares of our common stock, as further described in the definitive proxy statement filed with the U.S. Securities and Exchange Commission (the "SEC") on June 8, 2026 (the "Definitive Proxy Statement"). The parties expect the Transactions to close in the third quarter of 2026, subject to the satisfaction or waiver of the other customary closing conditions set forth in the Merger Agreement.

Important Information and Where to Find It

In connection with the Transactions, Catalyst has filed with the SEC the Definitive Proxy Statement. Catalyst may also file other documents with the SEC regarding the Transactions. This document is not a substitute for the Definitive Proxy Statement or any other document which Catalyst may file with the SEC. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE DEFINITIVE PROXY STATEMENT AND ANY OTHER RELEVANT DOCUMENTS THAT ARE FILED OR WILL BE FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO THESE DOCUMENTS, CAREFULLY AND IN THEIR ENTIRETY BECAUSE THEY CONTAIN OR WILL CONTAIN IMPORTANT INFORMATION ABOUT THE TRANSACTIONS AND RELATED MATTERS. Investors and security holders may obtain free copies of the Definitive Proxy Statement and other documents that are filed or will be filed with the SEC by Catalyst through the website maintained by the SEC at www.sec.gov or Catalyst's website at https://ir.catalystpharma.com/financial-information/sec-filings/default.aspx.

No Offer or Solicitation

This Current Report on Form 8-K is for information purposes only and is not intended to and does not constitute, or form part of, an offer, invitation or the solicitation of an offer or invitation to purchase, otherwise acquire, subscribe for, sell or otherwise dispose of any securities, or the solicitation of any vote or approval in any jurisdiction, pursuant to the Transactions or otherwise, nor shall there be any sale, issuance or transfer of securities in any jurisdiction in contravention of applicable law.

Participants in the Solicitation

Catalyst, Angelini Pharma, and certain of their respective directors and executive officers may be deemed to be participants in the solicitation of proxies in respect of the Transactions. Catalyst stockholders may obtain additional information regarding the direct and indirect interests of the participants in the solicitation of proxies in connection with the Transactions, including the interests of Catalyst directors and executive officers in the Transactions, which may be different than those of Catalyst stockholders generally, by reading the Definitive Proxy Statement and any other relevant documents that are filed or will be filed with the SEC relating to the Transactions. To the extent the holdings of Catalyst's securities by Catalyst's directors and executive officers have changed since the amounts set forth in the Definitive Proxy Statement, such changes will be reflected on Initial Statements of Beneficial Ownership on Form 3 or Statements of Change in Ownership on Form 4 filed with the SEC. You may obtain free copies of these documents using the sources indicated above.