A Form 144 notice of proposed sale was filed on October 28, 2026, by Ezgi N. Akcinar Atay, identified as a member of the immediate family of an officer and director of BillionToOne, Inc., covering 2,667 Class A shares to be sold through Fidelity Brokerage Services LLC on NASDAQ:BLLN.

Key Highlights

  • Proposed sale: 2,667 Class A shares with an aggregate market value of $314,706.00, with an approximate sale date of 10/28/2026.
  • Shares outstanding: The filing lists 42,644,388 Class A shares outstanding at the time of notice.
  • Acquisition: The 2,667 shares were acquired on 05/01/2024 as Pre-IPO Shares from the Issuer, with payment made in cash on 05/01/2024.
  • Rule 10b5-1 plan: The filing indicates a plan adoption or instruction date of 06/07/2026.
  • Family relationship: Ezgi N. Akcinar Atay is identified as the spouse of Oguzhan Atay, described in the filing as "an Officer and Director of the company."
  • Past 3-month sales aggregated: The filing lists prior Class A share sales by Oguzhan Atay, Ezgi N. Akcinar Atay, and the Atay 2021 Dynasty Trust, totaling multiple transactions from 08/03/2026 through 10/15/2026.

Proposed Sale Details and Aggregated Prior Transactions for BillionToOne, Inc.

According to the Form 144 filing, Ezgi N. Akcinar Atay proposes to sell 2,667 Class A shares of BillionToOne, Inc. (NASDAQ:BLLN) through Fidelity Brokerage Services LLC, located at 900 Salem Street, Smithfield, RI 02917. The aggregate market value of the proposed sale is listed as $314,706.00. The filing notes the approximate date of sale as 10/28/2026 and identifies the securities exchange as NASDAQ. The filing states that a Rule 10b5-1 plan or instruction was adopted on 06/07/2026.

The filing discloses that the shares to be sold were acquired on 05/01/2024 as Pre-IPO Shares from the Issuer, with full cash payment made on 05/01/2024. In the remarks section, the filing states: "Today's sale and sales within the past 3 months occurred in the account of Ezgi N. Akcinar Atay, who is the spouse of Oguzhan Atay, an Officer and Director of the company. There are also sales within the past 3 months which occurred in the Atay 2021 Dynasty Trust which were made by Icontrust Llc, trustee on the account. Oguzhan Atay is an account stakeholder in the Atay 2021 Dynasty Trust."

As required by Rule 144, the filing aggregates sales by related persons over the prior three months. These include Class A share sales by Oguzhan Atay on 08/03/2026 (32,500 shares, $4,450,834.75), 08/05/2026 (15,539 shares, $2,331,351.91), 09/14/2026 (24,999 shares, $2,507,908.84), 09/28/2026 (8,333 shares, $1,005,293.12), 10/12/2026 (16,667 shares, $1,563,124.60), 10/14/2026 (3,183 shares, $313,019.72), and 10/15/2026 (5,150 shares, $516,188.60). Sales by Ezgi N. Akcinar Atay in the same period include 12,500 shares on 08/03/2026 ($1,717,125.00), 5,332 shares on 09/14/2026 ($522,536.00), 2,666 shares on 09/28/2026 ($321,626.24), 2,667 shares on 10/12/2026 ($260,325.87), and 2,667 shares on 10/14/2026 ($261,366.00). The Atay 2021 Dynasty Trust sold 2,500 shares on 08/03/2026 for gross proceeds of $343,425.00.

What Was Disclosed

The filing is a Form 144 notice covering a proposed sale of 2,667 Class A shares of BillionToOne, Inc. by Ezgi N. Akcinar Atay, spouse of an officer and director, with an aggregate market value of $314,706.00 and an approximate sale date of 10/28/2026, conducted under a Rule 10b5-1 plan adopted 06/07/2026.