Fumihide Esaka, Chief Executive Officer and Director of Ambiq Micro, Inc. (NASDAQ:AMBQ), filed a Form 4 with the SEC disclosing option exercises and open-market sales of common stock on September 11 and September 15, 2026, with the filing signed on September 15, 2026.

Key Highlights

  • Option exercise on September 11, 2026: Esaka acquired 50,000 shares of common stock at an exercise price of $12.60 per share via transaction code M.
  • Sales on September 11, 2026: Esaka disposed of 42,083 shares at a weighted average price of $63.2661 and 7,917 shares at a weighted average price of $63.8583.
  • Option exercise on September 15, 2026: Esaka acquired 13,500 shares at an exercise price of $8.12 per share under a Rule 10b5-1 plan adopted May 15, 2026.
  • Sales on September 15, 2026: Esaka disposed of 3,785 shares, 9,615 shares, and 100 shares at weighted average prices of $59.5626, $60.5482, and $61.00, respectively, all under the Rule 10b5-1 plan.
  • Resulting ownership: Following all reported transactions, Esaka directly beneficially owned 460,460 shares of common stock.
  • Derivative securities remaining: After option exercises on both dates, Esaka held 144,279 shares underlying a stock option with a $12.60 exercise price and 58,507 shares underlying a stock option with an $8.12 exercise price.

Ambiq Micro CEO Exercises Options and Sells Shares Across Two Trading Dates

According to the Form 4 filed with the SEC, Esaka exercised stock options on two separate dates in September 2026. On September 11, 2026, he exercised options covering 19,007 shares expiring May 25, 2031, and 30,993 shares expiring July 20, 2034, both at an exercise price of $12.60, for a combined acquisition of 50,000 shares of Ambiq Micro common stock. Following those exercises, the filing shows his direct beneficial ownership stood at 510,460 shares before the same-day sales were recorded.

On September 11, 2026, Esaka then sold 42,083 shares at a weighted average price of $63.2661 per share, with individual transaction prices ranging from $62.70 to $63.70, and 7,917 shares at a weighted average price of $63.8583 per share, with prices ranging from $63.72 to $64.05. Both sales are identified as open-market disposals under transaction code S, according to the filing. Ambiq Micro is described in the filing as the issuer of the common stock transacted, with its principal address listed at 6500 River Place Blvd Building 7 Ste 200, Austin, Texas 78730.

On September 15, 2026, Esaka exercised an additional option covering 13,500 shares at an exercise price of $8.12, expiring February 20, 2029. He then sold 3,785 shares at a weighted average of $59.5626 (prices ranging from $58.95 to $59.94), 9,615 shares at a weighted average of $60.5482 (prices ranging from $59.96 to $60.80), and 100 shares at $61.00. The filing notes that the September 15 transactions occurred under a Rule 10b5-1 plan that Esaka adopted on May 15, 2026. The form was signed by Jeffrey Winzeler as Attorney-in-Fact on September 15, 2026. The filing also indicates a box was checked confirming the transactions were made pursuant to a contract, instruction, or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

What Was Disclosed

Esaka's Form 4 reports option exercises and open-market sales of Ambiq Micro common stock on September 11 and September 15, 2026, resulting in direct beneficial ownership of 460,460 shares, with remaining derivative positions in stock options at exercise prices of $12.60 and $8.12.