Oguzhan Atay, an officer and director of BillionToOne, Inc., filed a Form 144 notice of proposed sale on October 28, 2026, covering 8,333 Class A shares to be sold through Fidelity Brokerage Services LLC on NASDAQ.

Key Highlights

  • Proposed sale: Atay notified the SEC of a proposed sale of 8,333 Class A shares of BillionToOne, Inc., with an aggregate market value reported as $983,294.00.
  • Acquisition via stock option exercise: The 8,333 shares were acquired on October 28, 2026, through a stock option exercise from the issuer, with payment made in cash on the same date.
  • Shares outstanding: According to the filing, 42,644,388 Class A shares were outstanding at the time of the notice.
  • Rule 10b5-1 plan: The filing indicates a written trading plan was adopted on June 5, 2026.
  • Aggregated sellers: The filing lists prior sales by Oguzhan Atay, his spouse Ezgi N. Akcinar Atay, and the Atay 2021 Dynasty Trust as persons whose sales are required to be aggregated under Rule 144.
  • Prior three-month sales: Combined Class A share sales listed for aggregated persons between August 3, 2026, and October 15, 2026, total 136,503 shares across multiple transactions, according to the filing.

BillionToOne Officer Atay Proposes Class A Share Sale Following Stock Option Exercise

According to the Form 144 filing dated October 28, 2026, Oguzhan Atay, identified as both an officer and a director of BillionToOne, Inc. (NASDAQ:BLLN), proposed the sale of 8,333 Class A shares. The filing states those shares were acquired on October 28, 2026, via a stock option exercise from the issuer, with cash payment made on the same date. Fidelity Brokerage Services LLC, located at 900 Salem Street, Smithfield, RI 02917, is named as the broker for the proposed transaction. The aggregate market value of the shares to be sold is listed as $983,294.00.

The filing notes that Atay adopted a written trading plan under Rule 10b5-1 on June 5, 2026. In the remarks section, the filing discloses that sales within the past three months also occurred in accounts belonging to Ezgi N. Akcinar Atay, described as the spouse of Oguzhan Atay, and in the Atay 2021 Dynasty Trust, with Icontrust LLC serving as trustee. The filing states that "Oguzhan Atay is an account stakeholder in the Atay 2021 Dynasty Trust." These parties' sales are included in the three-month aggregation table as required under Rule 144.

The aggregated prior-sales table in the filing covers transactions dated from August 3, 2026, through October 15, 2026, across the accounts of Oguzhan Atay, Ezgi N. Akcinar Atay, and the Atay 2021 Dynasty Trust. Individual gross proceeds figures are listed for each transaction. BillionToOne, Inc. is headquartered at 1035 O'Brien Drive, Menlo Park, California 94025, and carries SEC file number 001-42934.

What Was Disclosed

Oguzhan Atay, an officer and director of BillionToOne, Inc., filed a Form 144 on October 28, 2026, for the proposed sale of 8,333 Class A shares acquired via stock option exercise, with an aggregate market value of $983,294.00, under a Rule 10b5-1 plan adopted June 5, 2026.