Kathryn Guarini, a director at Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN), filed a Form 4 on August 12, 2026, disclosing the exercise of 400 stock options and the same-day sale of 400 shares of common stock on August 10, 2026, under a pre-established Rule 10b5-1 trading plan.

Key Highlights

  • Option exercise: Guarini exercised 400 non-qualified stock options at a conversion price of $719.37 per share on August 10, 2026.
  • Share sale: 400 shares of common stock were sold at $800 per share on the same date.
  • Post-transaction ownership: Following the transactions, Guarini directly beneficially owned 603 shares of common stock.
  • Remaining options: 1,558 non-qualified stock options with an exercise price of $719.37 and an expiration date of January 2, 2035, remain directly held.
  • Rule 10b5-1 plan: Both transactions were made pursuant to a plan adopted on February 13, 2026, intended to comply with Rule 10b5-1(c).
  • Reporting person role: Guarini is identified in the filing as a director of Regeneron Pharmaceuticals, Inc.

Guarini's Option Exercise and Share Sale at Regeneron Pharmaceuticals

According to the filing, Kathryn Guarini exercised 400 non-qualified stock options in Regeneron Pharmaceuticals, Inc. on August 10, 2026, at an exercise price of $719.37 per share, coded as an "M" (option exercise) transaction. The acquisition brought her direct beneficial ownership of common stock to 1,003 shares immediately following the exercise, before the disposition was recorded.

On the same date, the filing discloses, Guarini sold 400 shares of common stock at a price of $800 per share, coded as an "S" (open market sale) transaction. After this disposition, her direct beneficial ownership of common stock stood at 603 shares. Both the exercise and the sale were reported as made pursuant to a plan intended to comply with Rule 10b5-1(c), adopted on February 13, 2026, according to the filing's explanation of responses.

The filing further notes that the non-qualified stock options subject to the exercise carry an expiration date of January 2, 2035. Regarding vesting, the filing states: "On the date of the Company's first annual meeting of shareholders following the date of grant, a portion of these stock options equal to the portion of one year that had passed from the date of grant became exercisable, and the remainder became exercisable on the first anniversary of the date of grant." Following the transactions, 1,558 non-qualified stock options remained directly held by Guarini, per the filing.

What Was Disclosed

The Form 4 filed August 12, 2026, reported that director Kathryn Guarini exercised 400 stock options at $719.37 and sold 400 shares at $800 on August 10, 2026, under a Rule 10b5-1 plan, leaving her with 603 shares and 1,558 options directly held.