BillionToOne, Inc. Chairman and CEO Oguzhan Atay filed a Form 4 on October 30, 2026, reporting stock option exercises and share sales of Class A Common Stock executed on October 28, 2026, under pre-established Rule 10b5-1 trading plans.

Key Highlights

  • Option exercise: Oguzhan Atay exercised a stock option for 8,333 shares of Class A Common Stock at $2.8 per share on October 28, 2026.
  • Direct sale: Atay disposed of 8,333 shares of Class A Common Stock at $118 per share, leaving 0 shares held directly following the transaction.
  • Spouse plan sale: An additional 2,667 shares were sold at $118 per share pursuant to a Rule 10b5-1 plan adopted by the reporting person's spouse on June 7, 2026.
  • Indirect holdings: Following all reported transactions, 146,501 shares of Class A Common Stock are beneficially owned indirectly by the reporting person through his spouse.
  • Remaining options: Atay retains 460,296 fully vested stock options with an exercise price of $2.8 and an expiration date of June 7, 2031.
  • 10b5-1 plans: Both the reporting person's direct transactions and the spouse's transactions were effected pursuant to Rule 10b5-1 trading plans, adopted June 5, 2026 and June 7, 2026, respectively.

Transaction Details for BillionToOne Chairman and CEO

According to the Form 4 filed with the SEC on October 30, 2026, Oguzhan Atay, Chairman and CEO of BillionToOne, Inc. (NASDAQ:BLLN), reported a series of transactions in Class A Common Stock on October 28, 2026. The filing indicates Atay exercised a stock option covering 8,333 shares at a conversion price of $2.8 per share (transaction code M). Those shares were then sold in the open market at $118 per share (transaction code S), reducing Atay's direct beneficial ownership in Class A Common Stock to 0 shares.

Separately, the filing discloses that 2,667 shares were disposed of at $118 per share pursuant to a Rule 10b5-1 trading plan adopted by the reporting person's spouse on June 7, 2026. Following this transaction, the reporting person's indirectly held shares - described in the filing as shares held by his spouse - stood at 146,501 shares of Class A Common Stock. The filing notes that Atay's direct transactions were made under a Rule 10b5-1 plan he adopted on June 5, 2026.

In Table II of the filing, Atay's remaining derivative securities consist of 460,296 stock options (right to buy) with an exercise price of $2.8 per share, expiring June 7, 2031, all of which the filing states "are fully vested and exercisable." The Form 4 was signed by Thomas P. Lynch as Attorney-in-Fact on October 30, 2026.

What Was Disclosed

The filing reports the exercise of 8,333 stock options at $2.8 per share and the sale of a total of 11,000 shares of Class A Common Stock at $118 per share by or on behalf of BillionToOne's Chairman and CEO, under pre-established Rule 10b5-1 trading plans.