Luo Mary Z. 4

What Happened
Jack Y. Zhang, a reported 10% owner of Amphastar Pharmaceuticals (AMPH), was granted equity awards on March 9, 2026. The filing shows 252,966 restricted stock units (RSUs) granted (180,504 and 72,462) and 521,810 derivative awards (likely option/derivative grants) for a combined 774,776 shares. On March 10, 2026, a total of 19,180 shares were withheld/disposed to satisfy tax withholding related to RSU vesting — 14,785 shares at $18.91 each ($279,584) and 4,395 shares at $18.91 each ($83,109), totaling $362,693. These grants are awards, not open-market purchases or sales.

Key Details

• Transaction dates: grants on 2026-03-09; tax-withholding disposals on 2026-03-10; Form 4 filed 2026-03-11 (appears timely).
• Prices reported for withheld shares: $18.91 per share; total withheld value ≈ $362,693.
• Award breakdown: 252,966 RSUs (non-derivative) and 521,810 derivative awards (total 774,776).
• Vesting: RSUs and the shares subject to options vest in four equal annual installments beginning March 9, 2027 (footnotes).
• Tax treatment: 19,180 shares were withheld to satisfy the reporting person’s tax liability (transaction code F).
• Record holdings: some securities are held of record by Mary Z. Luo and Applied Physics and Chemistry Laboratories, Inc.; the reporting persons are husband and wife (footnotes).
• Shares owned after the transaction are not specified in the supplied data.

Context

• These entries are equity awards (RSUs and derivative awards) with multi-year vesting — not open-market buys or indicative immediate insider selling. The withheld shares reflect a routine tax-withholding action (cashless settlement) rather than a discretionary sale.
• As a 10% owner, Zhang’s transactions reflect substantial ownership/compensation arrangements rather than typical executive open-market trading.