Luo Mary Z. 4

What Happened

• Jack Y. Zhang, a reported 10% owner of Amphastar Pharmaceuticals (AMPH), had 10,850 shares withheld on March 6, 2026 to satisfy tax withholding related to vested restricted stock units (RSUs). The withholding consisted of 7,773 shares (valued at $150,330) and 3,077 shares (valued at $59,509), each at $19.34 per share.
• This was a tax-withholding disposition (routine) tied to RSU vesting rather than an open-market sale or purchase, so it generally does not signal a deliberate market-timing decision.

Key Details

• Transaction date: 2026-03-06; Price per share: $19.34.
• Shares withheld/disposed: 7,773 and 3,077 (total 10,850); total value ≈ $209,839.
• Transaction code: F — shares withheld to satisfy tax liability on RSU vesting.
• Shares owned after the transaction: not specified in the filing summary.
• Filing date: 2026-03-10 — filed within the standard two business-day window, so the report appears timely.
• Footnotes: F2 notes some securities are held of record by Mary Z. Luo (reporting persons are husband and wife). F3 notes some shares are held of record by Applied Physics and Chemistry Laboratories, Inc., which the reporting persons and a related trust solely own.

Context

• This was a cashless/tax-withholding action tied to RSU vesting (routine administrative step), not a purchase or voluntary market sale. For retail investors, such withholdings are common and typically reflect tax obligations rather than a change in insider sentiment.
• As a 10% owner, Zhang's holdings and related entity ownership are more akin to principal ownership/estate structuring than executive trading; interpret accordingly.