BillionToOne shares: Trust proposes $184K sale

The proposed shares are held in the Dt 2021 Irrevocable Trust, with Icontrust LLC serving as trustee.

Rhea-AI Filing Summary

BillionToOne, Inc. (BLLN) is named as issuer in a Form 144 notice listing a proposed sale of 1,750 Class A shares, with an aggregate market value of $184,012.50 and an approximate sale date of October 5, 2026. The shares are held in the Dt 2021 Irrevocable Trust account, with Icontrust LLC as trustee; David Tsao is an account stakeholder. The notice lists 42,644,388 Class A shares outstanding.

Key Figures

Class A shares proposed for sale: 1,750 shares Aggregate market value: $184,012.50 Class A shares outstanding: 42,644,388 shares

3 metrics

Class A shares proposed for sale 1,750 shares Approximate sale date: October 5, 2026

Aggregate market value $184,012.50 Proposed Class A share sale

Class A shares outstanding 42,644,388 shares Issuer share count listed in the notice

Key Terms

Rule 144, Pre-IPO Shares, Irrevocable Trust

3 terms

Rule 144 regulatory

"definition of "person" in paragraph (a) of Rule 144"

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Pre-IPO Shares financial

"Pre-IPO Shares"

Irrevocable Trust technical

"Dt 2021 Irrevocable Trust"

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.

FAQ

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

How many BLLN Class A shares are listed for proposed sale?

The proposed sale is for 1,750 Class A shares, with an aggregate market value of $184,012.50 and an approximate sale date of October 5, 2026.

Who holds the shares in the proposed BLLN sale?

The shares are held in the Dt 2021 Irrevocable Trust account, with Icontrust LLC as trustee. David Tsao is an account stakeholder in the trust.

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

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Available on EDGAR 10/05/2026 - 10:50 AM Accepted by SEC EDGAR 10/05/2026 - 10:50 AM 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

144: Filer Information

Filer CIK	0002087127
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: 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: 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	1750	184012.50	42644388	10/05/2026	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: 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	12/30/2021	Pre-IPO Shares	Issuer			1750	12/30/2021	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: 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 OBrien Drive Menlo Park CA 94025	Class A	07/13/2026	20000	2497698.00
Dt 2021 Irrevocable Trust 1035 OBrien Drive Menlo Park CA 94025	Class A	07/13/2026	3500	439110.00
David Tsao 1035 OBrien Drive Menlo Park CA 94025	Class A	08/10/2026	10000	928600.00
Dt 2021 Irrevocable Trust 1035 OBrien Drive Menlo Park CA 94025	Class A	08/10/2026	3500	325010.00
David Tsao 1035 OBrien Drive Menlo Park CA 94025	Class A	08/25/2026	10000	1000000.00
David Tsao 1035 OBrien Drive Menlo Park CA 94025	Class A	09/09/2026	20000	1975400.00
Dt 2021 Irrevocable Trust 1035 OBrien Drive Menlo Park CA 94025	Class A	09/09/2026	1750	170695.00
David Tsao 1035 OBrien Drive Menlo Park CA 94025	Class A	09/24/2026	3333	416625.00

144: Remarks and Signature

Remarks	Today's sale and 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	10/05/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	06/08/2026
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/ Gary Redman, 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)