BillionToOne, Inc. officer and director David Tsao filed a Form 144 notice on November 2, 2026, disclosing a proposed sale of 20,000 Class A shares acquired through a stock option exercise, with an aggregate market value of $2,266,400.00.

Key Highlights

  • Proposed sale: 20,000 Class A shares of BillionToOne, Inc. (NASDAQ:BLLN) with an aggregate market value of $2,266,400.00.
  • Acquisition method: The shares were acquired via a stock option exercise from the issuer on November 2, 2026, with cash payment on the same date.
  • Shares outstanding: The filing lists 42,644,388 Class A shares outstanding at the time of the notice.
  • Approximate sale date: November 2, 2026, through Fidelity Brokerage Services LLC.
  • Rule 10b5-1 plan: The filing indicates a trading plan or instruction was adopted on June 5, 2026.
  • Prior three-month sales: David Tsao and the Dt 2021 Irrevocable Trust sold a combined 70,333 Class A shares between August 10, 2026 and October 5, 2026, generating gross proceeds totaling $6,163,292.50 across eight transactions.
  • Trust relationship: The filing notes that "David Tsao is an account stakeholder in the Dt 2021 Irrevocable Trust," whose sales are aggregated per Rule 144.

David Tsao's Proposed Class A Share Sale at BillionToOne

According to the Form 144 notice filed with the SEC on November 2, 2026, David Tsao, who is identified as both an officer and a director of BillionToOne, Inc., intends to sell 20,000 Class A shares of the company. The shares carry an aggregate market value of $2,266,400.00, according to the filing. The shares were obtained through a stock option exercise from the issuer on November 2, 2026, with cash payment made on the same date. The proposed sale is to be conducted through Fidelity Brokerage Services LLC, located at 900 Salem Street, Smithfield, RI 02917, on the NASDAQ exchange.

The filing discloses that Tsao adopted a written trading plan or gave trading instructions in reliance on Rule 10b5-1 under the Exchange Act, with a plan adoption date of June 5, 2026. As required under Rule 144, the notice also aggregates sales made in the prior three months. David Tsao personally sold Class A shares on August 10, August 25, September 9, September 24, and October 5, 2026, in amounts of 10,000, 10,000, 20,000, 3,333, and 20,000 shares, with gross proceeds of $928,600.00, $1,000,000.00, $1,975,400.00, $416,625.00, and $2,162,950.00, respectively.

Additionally, the Dt 2021 Irrevocable Trust, for which Icontrust LLC serves as trustee, sold 3,500 shares on August 10, 2026 (gross proceeds $325,010.00), 1,750 shares on September 9, 2026 (gross proceeds $170,695.00), and 1,750 shares on October 5, 2026 (gross proceeds $184,012.50). The filing states these sales are aggregated with Tsao's sales because "David Tsao is an account stakeholder in the Dt 2021 Irrevocable Trust."

What Was Disclosed

BillionToOne officer and director David Tsao filed a Form 144 notice proposing the sale of 20,000 Class A shares with an aggregate market value of $2,266,400.00, acquired via stock option exercise, with a Rule 10b5-1 plan adopted June 5, 2026.