BillionToOne executive sells 1,416 shares at $106.61

The SVP of Laboratory Operations' reported sale was made under a Rule 10b5-1 plan adopted on June 2, 2026.

Rhea-AI Filing Summary

BillionToOne, Inc. (BLLN) SVP of Laboratory Operations John Roderick ten Bosch sold 1,416 shares of Class A Common Stock at $106.61 per share on September 21, 2026. He directly held 23,635 shares after the sale. The transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by him on June 2, 2026.

Insider Trade Summary 10b5-1

Net Seller: 1,416 shares

Net Sell 1 txn

Insider ten Bosch John Roderick

Role SVP of Laboratory Operations

Sold 1,416 shs ($151K)

Type	Security	Shares	Price	Value
Sale	Class A Common Stock F1	1,416	$106.61	$151K

Holdings After Transaction: Class A Common Stock — 23,635 shares (Direct)

Footnotes (1)

1. F1. The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on June 2, 2026.

Key Figures

Shares sold: 1,416 shares Sale price: $106.61 per share Direct shares held after sale: 23,635 shares +1 more

4 metrics

Shares sold 1,416 shares September 21, 2026

Sale price $106.61 per share September 21, 2026

Direct shares held after sale 23,635 shares Following the September 21, 2026 sale

Rule 10b5-1 plan adoption date June 2, 2026 Trading plan pursuant to which the transaction was effected

Key Terms

Rule 10b5-1 trading plan, Class A Common Stock

2 terms

Rule 10b5-1 trading plan financial

"pursuant to a Rule 10b5-1 trading plan adopted"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

Class A Common Stock financial

"shares of Class A Common Stock"

Class A common stock is a category of a company’s shares that carries a specific set of ownership rights—most commonly defined voting power and claims on dividends—set out in the company’s charter. For investors it matters because the class determines how much influence you have over corporate decisions, the share’s likely dividend and trading behavior, and how it compares in value to other share classes, like choosing a particular seat with different privileges at the company’s decision-making table.

FAQ

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

How many BLLN shares did the SVP of Laboratory Operations sell, and at what price?

BillionToOne SVP of Laboratory Operations John Roderick ten Bosch sold 1,416 shares of Class A Common Stock at $106.61 per share on September 21, 2026. He directly held 23,635 shares after the sale, and the transaction was effected pursuant to a Rule 10b5-1 trading plan adopted on June 2, 2026.

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

Form 4 Insider Transactions: What Each Field Means →

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Available on EDGAR 09/23/2026 - 05:51 PM Accepted by SEC EDGAR 09/23/2026 - 05:50 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

ten Bosch John Roderick

(Last) (First) (Middle)

C/O BILLIONTOONE, INC.

1035 O'BRIEN DRIVE

(Street)

MENLO PARK CALIFORNIA 94025

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
BillionToOne, Inc. [ BLLN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SVP of Laboratory Operations

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/21/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Class A Common Stock	09/21/2026		S(1)		1,416	D	$106.61	23,635	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on June 2, 2026.

Remarks:

	/s/ Thomas P. Lynch, Attorney-in-Fact	09/23/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)