Every Form 4 that Amphastar Pharmaceuticals, Inc. (AMPH) has filed with the SEC in the last 12 months is listed below, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A Form 4 covers the transactions officers, directors and large holders report, so if you follow AMPH and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full AMPH filings page.
Amphastar Pharmaceuticals, Inc. CFO, EVP & Treasurer William J. Peters sold 4,139 shares of Common Stock at $25 per share on September 21, 2026, leaving him with 168,707 shares held directly. The reported balance is his direct position after the transaction, not the number of shares sold. The sale was made under a Rule 10b5-1 trading plan adopted on March 10, 2026.
Amphastar Pharmaceuticals, Inc. (AMPH) officer Rong Zhou, Senior EVP, Production Center, exercised options for 10,000 shares of common stock on September 16, 2026 at an exercise price of $13.35 per share and sold 10,000 shares the same day at a weighted average price of $23.94. Following the option exercise, Zhou held 19,424 stock options directly, and also has indirect ownership interests in common shares held by the Zhou Family Trust and by the reporting person’s spouse.
Amphastar Pharmaceuticals, Inc. (AMPH) executive Rong Zhou, Senior EVP, Production Center, reported selling 3,187 shares of common stock on September 2, 2026 in an open-market or private transaction at a weighted average price of $23.6291 per share, with trade prices ranging from $23.62 to $23.69.
After this sale, Zhou directly holds 169,203 shares of Amphastar common stock, including 836 shares acquired on May 31, 2026 under the company’s 2014 Employee Stock Purchase Plan. Additional indirect holdings are reported through the Zhou Family Trust and the reporting person’s spouse. No Rule 10b5-1 trading plan is reported.
Amphastar Pharmaceuticals, Inc. director Richard K. Prins reported a sale of 7,973 shares of common stock on 2026-08-11 in a sale in open market or private transaction at $20.30 per share. Following this transaction, he directly holds 29,625 shares of Amphastar common stock.
Amphastar Pharmaceuticals, Inc. director and CFO/EVP/Treasurer William J. Peters reported an options exercise and share sale. On August 7, 2026, he exercised 5,053 Employee Stock Options at an exercise price of $19.79 per share, receiving 5,053 shares of common stock and closing out that option grant. The same day, he sold 8,180 shares of common stock at $22.48 per share in a transaction described as a sale in the open market or a private transaction. The sale was executed pursuant to a Rule 10b5-1 trading plan adopted on March 10, 2026. A related holding footnote states that reported common stock holdings include 910 shares acquired on May 31, 2026 under the company’s 2014 Employee Stock Purchase Plan.
Pierce Anthony T reported acquisition or exercise transactions in this Form 4 filing.
Amphastar Pharmaceuticals director Anthony T. Pierce received equity compensation on July 9, 2026, consisting of 7,886 restricted stock units and 16,646 stock options. All RSUs and options vest on July 9, 2027, with the options exercisable at $19.02 per share and expiring on July 9, 2036. These are grants, not open‑market purchases or sales.
Amphastar Pharmaceuticals director Richard K. Prins reported new equity awards and prior gifting activity. On June 1, 2026 he received 8,143 shares of Common Stock in the form of restricted stock units, all vesting on June 1, 2027, and a stock option for 17,365 shares at an exercise price of $18.42 per share that also vests on June 1, 2027 and expires on June 1, 2036. A previously reported bona fide gift on August 19, 2024 transferred 1,500 shares of Common Stock. Following the latest transactions, he beneficially owned 37,598 shares as of June 1, 2026 after an account reconciliation noted in the filing.
Amphastar Pharmaceuticals, Inc. director Lee Howard reported routine equity compensation and related tax withholding. On June 1, 2026, he received 8,143 shares of Common Stock in the form of restricted stock units that will fully vest on June 1, 2027, and was granted stock options for 17,365 shares at an exercise price of $18.42 per share, expiring on June 1, 2036. On June 2, 2026, 769 shares of Common Stock were withheld to cover his tax liability from RSU vesting. After these transactions, he directly holds 159,350 shares of Common Stock.
Amphastar Pharmaceuticals director Michael A. Zasloff received new equity awards in the form of stock and options. On June 1, 2026, he was granted 8,143 shares of common stock represented by restricted stock units that vest on June 1, 2027. He also received a stock option for 17,365 shares of common stock at an exercise price of $18.42 per share, expiring on June 1, 2036, with all option shares vesting on June 1, 2027. Following these grants, he directly owns 37,667 shares of Amphastar common stock. These awards represent compensation rather than open-market purchases or sales.
Amphastar Pharmaceuticals director Diane G. Gerst received equity compensation consisting of 8,143 shares of common stock in the form of restricted stock units and a stock option for 17,365 shares at an exercise price of $18.42 per share. All RSUs and option shares vest on June 1, 2027. Following these awards, she directly holds 31,899 shares of common stock.
Amphastar Pharmaceuticals director David Russell Gaugh received new equity awards as part of his compensation. He was granted 8,143 shares of Common Stock in the form of restricted stock units, which fully vest on June 1, 2027. Following this grant, he directly holds 14,447 Common Stock shares. He was also awarded stock options covering 17,365 shares of Common Stock at an exercise price of $18.42 per share. All of these options vest on June 1, 2027 and expire on June 1, 2036, giving him the right to buy shares at that fixed price if the company performs well over time.
Amphastar Pharmaceuticals director Deflin Gayle received new equity compensation awards. On June 1, 2026, Gayle acquired 8,143 shares of Common Stock through restricted stock units that vest on June 1, 2027. Gayle also received stock options for 17,365 shares at an exercise price of $18.42 per share, with all option shares vesting on June 1, 2027 and expiring on June 1, 2036. Following the stock grant, Gayle directly holds 19,057 shares of Common Stock, in addition to the newly granted options. These are compensation-related awards rather than open-market purchases or sales.
Amphastar Pharmaceuticals director and EVP Liawatidewi Yakob reported a tax-withholding share disposition related to RSU vesting. On 2026-03-15, 1,033 shares of Common Stock were withheld at $18.18 per share to cover her tax liability from vested restricted stock units.
After this non-market tax-withholding event, she directly holds 121,892 shares of Amphastar Common Stock. An additional 2,459 shares are held indirectly by the Yakob and Sunmoon Trust dated July 25, 2013, for which she serves as a trustee.
Amphastar Pharmaceuticals senior executive Rong Zhou reported a routine tax-withholding share disposition tied to restricted stock units. On March 15, 2026, 1,225 shares of common stock were withheld at $18.18 per share to satisfy tax liabilities from RSU vesting.
After this transaction, Zhou directly held 171,554 Amphastar shares. Footnotes show additional indirect holdings of 99,668 shares held by the Zhou Family Trust, where Zhou serves as trustee, and 5,000 shares held by Zhou’s spouse.
Amphastar Pharmaceuticals CFO William J. Peters reported a routine tax-related share disposition. On the vesting of restricted stock units, 1,973 shares of common stock were withheld at $18.18 per share to satisfy his tax liability, rather than sold on the open market.
After this withholding, Peters directly holds 175,063 shares of Amphastar common stock. This filing reflects a compensation-driven, non-discretionary tax-withholding event, not an open-market purchase or sale decision.
Amphastar Pharmaceuticals reported insider share movements tied to routine tax withholding on vested restricted stock units. On the reported date, entities associated with executives Jack Y. Zhang and Mary Z. Luo delivered a total of 12,692 shares of common stock at $18.18 per share to satisfy tax liabilities, classified as tax-withholding dispositions rather than open-market sales.
Following these transactions, Zhang is shown holding 2,990,052 shares directly, while related entities report 6,827,679 shares held indirectly. Luo-related holdings include 1,245,125 shares held of record. These entries reflect compensation-related mechanics and leave substantial equity positions in place.
Amphastar Pharmaceuticals CFO William J. Peters reported equity compensation and related tax withholding transactions. On March 9, 2026, he received 58,693 shares of Common Stock in the form of restricted stock units that vest in four equal annual installments beginning on March 9, 2027.
On the same date, he was granted an employee stock option covering 121,071 shares of Common Stock at an exercise price of $19.21 per share, expiring in 2036, also vesting in four equal annual installments beginning on March 9, 2027. On March 10, 2026, 3,297 shares of Common Stock were withheld to cover his tax liabilities from RSU vesting, leaving him with 177,036 shares of Common Stock held directly.
Amphastar Pharmaceuticals, Inc. senior executive Rong Zhou reported routine equity compensation and related tax withholding. On March 9, 2026, Zhou received 39,432 restricted stock units (RSUs) and an option for 81,341 shares of common stock at $19.21 per share, both vesting in four equal annual installments beginning on March 9, 2027. A separate entry on March 10, 2026 shows 2,215 common shares withheld at $18.91 per share to cover taxes on RSU vesting, which is characterized as a tax-withholding disposition rather than an open-market sale. After these transactions, Zhou holds 172,779 common shares directly, in addition to indirect holdings of 99,668 shares through the Zhou Family Trust and 5,000 shares held by a spouse, plus the newly granted option for 81,341 shares.
Amphastar Pharmaceuticals EVP Liawatidewi Yakob reported routine equity compensation and related tax withholding. She received 35,450 shares of Common Stock in the form of restricted stock units that vest in four equal annual installments beginning on March 9, 2027. She was also granted employee stock options for 73,126 shares of Common Stock at an exercise price of $19.21 per share, vesting in four equal annual installments starting on March 9, 2027 and expiring in 2036. In connection with RSU vesting, 1,870 shares of Common Stock were withheld to satisfy tax liabilities, a non‑market disposition. Following these events, she holds 122,925 Common Stock shares directly, 2,459 shares indirectly through the Yakob and Sunmoon Trust, and the newly granted 73,126 stock options.
Amphastar Pharmaceuticals insiders reported routine equity compensation and related tax withholding. CEO Jack Y. Zhang and COO Mary Z. Luo, who are also major shareholders and directors, received grants of restricted stock units (RSUs) and employee stock options tied to common stock. The RSUs, totaling 180,504 shares held directly and 72,462 shares held indirectly, vest in four equal annual installments beginning on March 9, 2027. They also received employee stock options for 372,338 shares held directly and 149,472 shares held indirectly, with a $19.21 exercise price and the same four-year vesting schedule. In connection with RSU vesting, 14,785 directly held shares and 4,395 indirectly held shares of common stock were withheld at $18.91 per share to cover tax liabilities, a non‑market transaction. Following these updates, reported holdings include 3,014,621 shares of common stock held directly, 1,252,428 shares held indirectly, and 6,827,679 additional shares held indirectly through Applied Physics and Chemistry Laboratories, Inc. and a related trust.
Amphastar Pharmaceuticals director and CFO William J. Peters reported a routine tax-related share disposition. On March 6, 2026, 2,146 shares of common stock were withheld at $19.34 per share to satisfy his tax liability from vesting restricted stock units. After this withholding, he directly owned 121,640 shares of Amphastar common stock.
Amphastar Pharmaceuticals senior executive Rong Zhou reported a routine tax-related share disposition. On March 6, 2026, 1,357 shares of common stock were withheld at $19.34 per share to cover taxes from vesting restricted stock units. After this withholding, Zhou directly held 135,562 shares, with additional indirect holdings of 99,668 shares through the Zhou Family Trust and 5,000 shares held by the spouse, as noted in the footnotes. This filing reflects compensation- and tax-driven activity rather than an open-market trade.
Amphastar Pharmaceuticals EVP Liawatidewi Yakob reported a routine tax-related share disposition. On March 6, 2026, 1,144 shares of common stock were withheld at $19.34 per share to cover taxes on vesting restricted stock units, not as an open-market sale.
After this withholding, Yakob directly holds 89,345 shares of Amphastar common stock and indirectly holds 2,459 shares through the Yakob and Sunmoon Trust dated July 25, 2013, where she serves as trustee.
Amphastar Pharmaceuticals director and CEO Jack Y. Zhang reported routine tax-related share withholdings tied to restricted stock unit vesting. On March 6, 2026, a total of 10,850 shares of common stock were withheld to satisfy tax liabilities, rather than sold on the open market.
After these withholdings, Zhang holds 2,834,117 shares directly. Additional indirect holdings include 1,179,966 shares held of record by his spouse, Mary Z. Luo, and 6,827,679 shares held through Applied Physics and Chemistry Laboratories, Inc. and a related family trust.
Amphastar Pharmaceuticals insiders reported tax-related share withholdings tied to equity compensation, not open-market sales. CEO and Chief Scientific Officer Jack Y. Zhang had 5,769 shares of common stock withheld at $19.96 per share to satisfy tax liabilities from vesting restricted stock units, leaving 2,841,890 shares held directly.
Additional tax-withholding dispositions of 2,432 common shares at $19.96 per share were reported as indirectly owned, with 1,183,043 indirect shares remaining. Footnotes state that some securities are held of record by Mary Z. Luo and that 6,827,679 shares are held of record by Applied Physics and Chemistry Laboratories, Inc., which is owned by the reporting persons and The Bill Luobei Zhang 2004 Irrevocable Trust.
Amphastar Pharmaceuticals senior executive Rong Zhou reported a small share disposition related to taxes, not an open-market sale. On the RSU vesting date, 1,124 shares of common stock were withheld at $19.96 per share to cover Zhou’s tax liability, leaving 136,919 shares held directly. In addition, 99,668 shares are held indirectly through the Zhou Family Trust, where Zhou serves as trustee, and 5,000 shares are held by Zhou’s spouse.
Amphastar Pharmaceuticals director and EVP Liawatidewi Yakob reported a tax-related share disposition. On March 4, 2026, 965 shares of common stock were withheld at $19.96 per share to satisfy her tax liability upon vesting of restricted stock units.
After this tax-withholding disposition, she directly held 90,489 common shares. She also indirectly held 2,459 shares through the Yakob and Sunmoon Trust dated July 25, 2013, which includes 545 shares acquired on May 31, 2025 under Amphastar’s 2014 Employee Stock Purchase Plan.
Amphastar Pharmaceuticals CFO William J. Peters had 1,744 shares of common stock withheld at $19.96 per share to cover taxes from vesting restricted stock units. After this tax-withholding disposition, he directly owns 123,786 shares, which include 545 shares acquired under the company’s 2014 Employee Stock Purchase Plan.
Amphastar Pharmaceuticals' senior executive reports option exercise and share sale. The Senior EVP, Production Center exercised an employee stock option to acquire 9,787 shares of Amphastar Pharmaceuticals common stock at an exercise price of $11.33 per share on 12/17/2025. On the same day, 9,787 common shares were sold at a weighted average price of $26.1959 per share, with individual sale prices ranging from $25.97 to $26.50.
After these transactions, the reporting person directly owns 138,043 common shares. In addition, 99,668 shares are held by the Zhou Family Trust, for which the reporting person serves as trustee, and 5,000 shares are held by the reporting person’s spouse. The option shares were fully vested and immediately exercisable at the time of exercise.
Amphastar Pharmaceuticals reported that one of its directors sold Amphastar common stock in two open-market transactions. On December 11, 2025, the director sold 1,737 shares at $25.688 per share. On December 12, 2025, the director sold 2,426 shares at a weighted average price of $25.9226 per share, with individual trades ranging from $25.9225 to $25.945.
After these sales, the director beneficially owned 71,368 shares of Amphastar common stock, held directly. The report states that full detail on the number of shares sold at each separate price is available upon request from the issuer, any security holder, or the SEC staff.
Amphastar Pharmaceuticals director reports option exercise and share sale. A director of Amphastar Pharmaceuticals, Inc. (AMPH) exercised a stock option for 4,179 shares of common stock on 11/25/2025 at an exercise price of $16.69 per share. On the same date, the director sold 4,179 shares of common stock in an open-market transaction at a weighted average price of $27.1006 per share, with individual sale prices ranging from $27.10 to $27.125. After these transactions, the director beneficially owns 35,183 shares of Amphastar common stock held directly. The option exercised covered fully vested, immediately exercisable shares and now has a remaining balance of zero derivative securities.
Amphastar Pharmaceuticals, Inc. (AMPH) reported an insider transaction by a director involving company common stock. On 11/13/2025, the director exercised a stock option for 16,679 shares of common stock at an exercise price of $16.69 per share and acquired those shares. On the same date, the director sold 16,679 shares of common stock at a weighted average price of $26.4906 per share, with individual sale prices ranging from $26.43 to $26.57. After these transactions, the director beneficially owned 75,531 shares of Amphastar common stock directly. The stock option covering 16,679 shares, which was fully vested and immediately exercisable and had an expiration date of 06/07/2026, now shows 0 derivative securities remaining beneficially owned.
Amphastar Pharmaceuticals (AMPH): director sale reported. On 11/03/2025, a director sold 500 shares of common stock at a weighted average price of $25.2662 under a Rule 10b5-1 trading plan adopted on November 26, 2024. The trades occurred at prices ranging from $25.00 to $25.47. After this transaction, the reporting person beneficially owns 75,531 shares, held directly.