Liawatidewi Yakob 4

What Happened
Liawatidewi Yakob, EVP Corporate Administration Center and a company director at Amphastar Pharmaceuticals, received equity awards on March 9, 2026: 35,450 restricted stock units (RSUs) and an additional 73,126 derivative award units (total 108,576 units) at $0.00 per share. On March 10, 2026, 1,870 shares were withheld (disposed) to satisfy tax liabilities at $18.91 per share, totaling $35,362. These transactions are awards and a routine tax-withholding, not open-market purchases.

Key Details

• Transaction dates: awards on 2026-03-09; tax-withholding on 2026-03-10. Form 4 filed 2026-03-11 (timely).
• Award specifics: 35,450 RSUs (grant A) and 73,126 derivative award units (A — derivative), both reported at $0.00 acquisition price.
• Withholding: 1,870 shares withheld at $18.91 each to cover taxes (total $35,362) (code F).
• Vesting: RSUs and derivative awards vest in four equal annual installments beginning March 9, 2027 (footnotes F1 and F4).
• Record holding: some shares are held of record by the Yakob and Sunmoon Trust dated July 25, 2013, for which Yakob is trustee (F3).
• Shares owned after the transactions were not specified on the Form 4.

Context
RSUs and similar derivative awards vest over time and are common executive compensation; the withholding of a small number of shares to satisfy taxes is a routine administrative action and not a directional trade. The derivative award is subject to the same multi-year vesting schedule. This filing does not indicate an open-market purchase or a voluntary sale beyond tax withholding.