Akshay Rai - 06 Nov 2025 Form 4 Insider Report for BillionToOne, Inc. (BLLN)

Role: Director
Signature: /s/ Thomas P. Lynch, Attorney-in-Fact
Issuer symbol: BLLN
Transactions as of: 06 Nov 2025
Transactions value $: $0
Form type: 4
Filing time: 10 Nov 2025, 21:45:47 UTC
Previous filing: 05 Nov 2025
Next filing: 12 Nov 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Rai Akshay	Director	2180 SAND HILL ROAD, STE. 100, MENLO PARK	/s/ Thomas P. Lynch, Attorney-in-Fact	10 Nov 2025	0002087877

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	BLLN	Common Stock	Award	$0	+8.33K		$0.00	8.33K	06 Nov 2025	Direct	F1
transaction	BLLN	Common Stock	Conversion of derivative security		+2.68K	+32.11%		11K	07 Nov 2025	Direct	F2, F3
transaction	BLLN	Common Stock	Conversion of derivative security		+1.78M			1.78M	07 Nov 2025	See Footnote	F2, F3, F4
transaction	BLLN	Common Stock	Other		-11K	-100%		0	07 Nov 2025	Direct	F5
transaction	BLLN	Common Stock	Other		-1.78M	-100%		0	07 Nov 2025	See Footnote	F4, F5
transaction	BLLN	Class A Common Stock	Other		+11K			11K	07 Nov 2025	Direct	F5
transaction	BLLN	Class A Common Stock	Other		+1.78M			1.78M	07 Nov 2025	See Footnote	F4, F5

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	BLLN	Series D Convertible Preferred Stock	Conversion of derivative security		-2.68K	-100%		0	07 Nov 2025	Common Stock	2.68K		Direct	F3
transaction	BLLN	Series D Convertible Preferred Stock	Conversion of derivative security		-1.78M	-100%		0	07 Nov 2025	Common Stock	1.78M		See Footnotes	F3, F4

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Each restricted stock unit (RSU) represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest over three years in equal annual installments on the anniversary of November 6, 2025, subject to the Reporting Person's continuous service to the Issuer through each such vesting date.
F2	The total represents shares received upon conversion of shares of Series D Convertible Preferred Stock.
F3	The reported security converted into the Issuer's Common Stock on a one-for-one basis automatically immediately prior to the closing of the Issuer's initial public offering of Class A common stock (the "Offering") without payment of further consideration. The shares have no expiration date.
F4	The reported securities are directly held by Wipro Enterprises Private Limited (Wipro), of which Mr. Rai is the nominee/investor director appointed by Wipro Enterprises Limited. Mr. Rai will not have voting or dispositive control of these securities while such securities are held by Wipro and thus disclaims beneficial ownership of such securities.
F5	Pursuant to a reclassification exempt under Rule 16b-7, each share of Common Stock was automatically reclassified into one share of Class A common stock immediately prior to the completion of the Offering.