Amgen Statement on IRS Notice Related to Horizon Acquisition

On October 6, 2023, Amgen Inc., a U.S. resident corporation and taxpayer, through its subsidiary, Pillartree Limited, acquired all the outstanding shares of Horizon Therapeutics plc not previously owned by Amgen Inc. or its subsidiaries. Following the posting of this notice, Amgen Inc. will make elections under Section 338(g) of the Internal Revenue Code of 1986, as amended with respect to the acquisition of Horizon Therapeutics plc. This communication serves as notice of the elections. To access the full notice and related documents, please see the attached.

Notice of IRC § 338 Election Pursuant to Treasury Regulations § 1.338-2(e)(4)

Form 8023