Oguzhan Atay, Chairman and CEO of BillionToOne, Inc. (NASDAQ:BLLN), filed a Form 4 on November 4, 2026, disclosing option exercises and multiple sales of Class A Common Stock executed on November 2, 2026, under a pre-established Rule 10b5-1 trading plan.

Key Highlights

  • Option exercises: Atay exercised stock options covering 16,667 shares and 8,334 shares of Class A Common Stock at an exercise price of $2.8 per share on November 2, 2026.
  • Direct share sales: Following the exercises, Atay sold shares in multiple tranches on November 2, 2026, at weighted average prices ranging from approximately $107.3142 to $112.4416 per share, reducing his direct beneficial ownership to 0 shares.
  • Indirect sales by spouse: Two additional sales of 2,667 shares each at $113.17 per share were reported as indirect holdings disposed of through a separate Rule 10b5-1 plan adopted by the reporting person's spouse on June 7, 2026, leaving 141,167 shares held indirectly.
  • 10b5-1 plan: Atay's direct transactions were made pursuant to a Rule 10b5-1 trading plan he adopted on June 5, 2026.
  • Remaining options: Following the exercises, Atay held 435,295 stock options (right to buy) directly, with an exercise price of $2.8 and an expiration date of June 7, 2031, according to the filing.

BillionToOne CEO Reports November 2 Option Exercises and Share Dispositions

According to the Form 4 filed with the SEC on November 4, 2026, Oguzhan Atay, who serves as Chairman and CEO of BillionToOne, Inc. (NASDAQ:BLLN), exercised two tranches of fully vested stock options on November 2, 2026. The first exercise converted 16,667 options into Class A Common Stock at $2.8 per share, and the second converted 8,334 options at the same price. BillionToOne is a molecular diagnostics company listed on the NASDAQ exchange.

Following those exercises, the filing reports that Atay sold shares directly across multiple price tranches on the same date. The weighted average sale prices reported ranged from $107.3142 to $112.4416 per share across the direct transactions. Each weighted average price reflects sales conducted in multiple sub-transactions; the filing notes that full detail on individual transaction prices within each range is available upon written request. After the final direct sale of 200 shares at a weighted average price of $112.39 per share, Atay's direct beneficial ownership stood at 0 shares, as reported in the filing.

Separately, two dispositions of 2,667 shares each at $113.17 per share were reported as indirect holdings, representing shares held by Atay's spouse. The filing states those transactions were made under a Rule 10b5-1 plan adopted by the spouse on June 7, 2026. Following those sales, indirect beneficial ownership stood at 141,167 shares, according to the filing. All of Atay's direct transactions were carried out under his own Rule 10b5-1 plan, adopted on June 5, 2026.

What Was Disclosed

The filing disclosed option exercises totaling 25,001 shares of Class A Common Stock at $2.8 per share, followed by sales of directly and indirectly held shares on November 2, 2026, all conducted under separate Rule 10b5-1 trading plans, with 435,295 options remaining directly held.