BillionToOne insider plans 10,000-share sale

BillionToOne (symbol BLLN) has a Form 144/A filing indicating that insider David Tsao plans to sell 10,000 Class A shares through Fidelity Brokerage Services on 08/10/2026, following a stock option exercise.

Rhea-AI Filing Summary

BillionToOne (symbol BLLN) has a Form 144/A filing indicating that insider David Tsao plans to sell 10,000 Class A shares through Fidelity Brokerage Services on 08/10/2026, following a stock option exercise. The planned sale reflects an aggregate market value of $928,600.00 on NASDAQ.

Over the prior three months, reported sales of Class A shares included 20,000 shares for $2,045,326.00 and 20,000 shares for $2,497,697.77 by David Tsao, plus 3,500 shares for $355,145.00 and 3,500 shares for $439,110.00 by the DT 2021 Irrevocable Trust.

Key Figures

Planned shares to be sold: 10,000 shares Planned sale value: $928,600.00 Sale on 06/15/2026 (Tsao): 20,000 shares for $2,045,326.00 +3 more

6 metrics

Planned shares to be sold 10,000 shares Class A shares to be sold on 08/10/2026

Planned sale value $928,600.00 Aggregate market value for 10,000 Class A shares

Sale on 06/15/2026 (Tsao) 20,000 shares for $2,045,326.00 Class A shares sold by David Tsao

Sale on 07/13/2026 (Tsao) 20,000 shares for $2,497,697.77 Class A shares sold by David Tsao

Trust sale on 06/15/2026 3,500 shares for $355,145.00 Class A shares sold by DT 2021 Irrevocable Trust

Trust sale on 07/13/2026 3,500 shares for $439,110.00 Class A shares sold by DT 2021 Irrevocable Trust

Key Terms

Stock Option Exercise, Irrevocable Trust, Aggregate market value

3 terms

Stock Option Exercise financial

"Class A | 08/10/2026 | Stock Option Exercise | Issuer"

A stock option exercise is the act of using a previously granted right to buy shares of a company's stock at a specific, predetermined price by paying that price and receiving the shares. It matters to investors because exercising changes who owns the shares (which can dilute existing ownership), can trigger taxable events and shift potential gains or losses, and affects voting power and the company’s outstanding share count—like turning a voucher into an actual product that becomes part of circulating supply.

Irrevocable Trust financial

"Dt 2021 Irrevocable Trust 1035 O'Brien Drive Menlo Park CA"

An irrevocable trust is a legal arrangement where an owner transfers assets into a separate entity managed by a trustee and gives up the power to modify or reclaim those assets. For investors it matters because putting stock or other holdings into such a trust can change who controls and benefits from the assets, affect taxes and creditor protection, and influence how easy it is to sell or value those holdings—like placing valuables in a locked safe overseen by someone else.

Aggregate market value financial

"Class A ... 10000 | 928600.00 | 42644388 | 08/10/2026"

Aggregate market value is the combined price you would pay to buy all outstanding shares of a company or all companies in a group at current market prices — essentially the sum of each stock’s market capitalization. It matters to investors because it shows the overall size and weight of an investment or sector (like the total cost to buy every piece of a puzzle), helps compare scale across companies or markets, and influences index composition and risk exposure.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction does BLLN’s latest Form 144/A report?

The Form 144/A for BLLN reports that insider David Tsao intends to sell 10,000 Class A shares on 08/10/2026 after a stock option exercise, with an aggregate market value of $928,600.00 on NASDAQ.

How many BLLN shares has David Tsao sold in the past three months?

According to the filing, David Tsao sold 20,000 Class A shares for $2,045,326.00 on 06/15/2026 and another 20,000 shares for $2,497,697.77 on 07/13/2026, all in BillionToOne (BLLN) stock.

What transactions did the DT 2021 Irrevocable Trust report for BLLN stock?

The DT 2021 Irrevocable Trust reported sales of 3,500 Class A shares of BLLN for $355,145.00 on 06/15/2026 and 3,500 shares for $439,110.00 on 07/13/2026, as listed in the Form 144/A.

What is the nature of the planned BLLN share sale on 08/10/2026?

The planned 08/10/2026 transaction for BLLN is tied to a stock option exercise, with 10,000 Class A shares to be sold for cash through Fidelity Brokerage Services, as specified in the Form 144/A filing.

Which broker is handling the planned BLLN insider share sale?

The planned sale of 10,000 Class A shares of BLLN is to be executed through Fidelity Brokerage Services LLC, located in Smithfield, Rhode Island, according to the Form 144/A disclosure.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 08/10/2026 - 12:52 PM EDT Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144/A

144/A: Filer Information

Filer CIK	0002087127
Filer CCC	XXXXXXXX
Previous Accession Number Of The Filing	0001959173-26-005805
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144/A: Issuer Information

Name of Issuer	BillionToOne, Inc.
SEC File Number	001-42934
Address of Issuer	1035 O'BRIEN DRIVE MENLO PARK CALIFORNIA 94025
Phone	650-460-2551
Name of Person for Whose Account the Securities are To Be Sold	Tsao David
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer
Relationship to Issuer	Director

144/A: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Class A	Fidelity Brokerage Services LLC 900 Salem Street Smithfield RI 02917	10000	928600.00	42644388	08/10/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144/A: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Class A	08/10/2026	Stock Option Exercise	Issuer			10000	08/10/2026	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144/A: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
David Tsao 1035 O'Brien Drive Menlo Park CA 94025	Class A	06/15/2026	20000	2045326.00
Dt 2021 Irrevocable Trust 1035 O'Brien Drive Menlo Park CA 94025	Class A	06/15/2026	3500	355145.00
David Tsao 1035 O'Brien Drive Menlo Park CA 94025	Class A	07/13/2026	20000	2497697.77
Dt 2021 Irrevocable Trust 1035 O'Brien Drive Menlo Park CA 94025	Class A	07/13/2026	3500	439110.00

144/A: Remarks and Signature

Remarks	This Form 144 amends and supersedes the Form 144 filed on August 10, 2026. The Securities Sold During the Past 3 Months is corrected. Sales within the past 3 months occurred in the account of the Dt 2021 Irrevocable Trust by Icontrust Llc, trustee on the account. David Tsao is an account stakeholder in the Dt 2021 Irrevocable Trust.
Date of Notice	08/10/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	03/06/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Daniel Tucci, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for David Tsao
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)