Humming Bird Ventures Management NV - 07 Nov 2025 Form 4 Insider Report for BillionToOne, Inc. (BLLN)

Role: 10%+ Owner
Signature: Hummingbird Ventures Management NV /s/ Lukas Decoster 49/9 CommV, represented by its permanent representative Lukas Decoster, Director
Issuer symbol: BLLN
Transactions as of: 07 Nov 2025
Net transactions value: $0
Form type: 4
Filing time: 20 Jan 2026, 19:27:56 UTC
Previous filing: 20 Jan 2026
SEC: View on sec.gov

Reporting Owners (8)

Name	Relationship	Address	Signature	Signature date	CIK
Humming Bird Ventures Management NV	10%+ Owner	SQUARE VICTORIA REGAIN 1, SINT-JOOST-TEN-NODE, BELGIUM	Hummingbird Ventures Management NV /s/ Lukas Decoster 49/9 CommV, represented by its permanent representative Lukas Decoster, Director	20 Jan 2026	0002099044
Hummingbird Opportunity Fund II CommV	10%+ Owner	SQUARE VICTORIA REGAIN 1, SINT-JOOST-TEN-NODE, BELGIUM	/s/ Barend Van den Brande	20 Jan 2026	0002099049
Hummingbird Ventures III CommV	10%+ Owner	SQUARE VICTORIA REGAIN 1, SINT-JOOST-TEN-NODE, BELGIUM	/s/ Lukas Decoster	20 Jan 2026	0002099047
Hummingbird Dragons CommV	10%+ Owner	SQUARE VICTORIA REGAIN 1, SINT-JOOST-TEN-NODE, BELGIUM	Hummingbird Opportunity Fund II CommV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	20 Jan 2026	0002099040
Hummingbird Collective CommV	10%+ Owner	SQUARE VICTORIA REGAIN 1, SINT-JOOST-TEN-NODE, BELGIUM	Hummingbird Ventures III CommV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	20 Jan 2026	0002099041
HB&Q NV (HB&Q COMPARTMENT III)	10%+ Owner	SQUARE VICTORIA REGAIN 1, SINT-JOOST-TEN-NODE, BELGIUM	Hummingbird Dragons CommV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	20 Jan 2026	0002099035
Van den Brande Barend	10%+ Owner	SQUARE VICTORIA REGAIN 1, SINT-JOOST-TEN-NODE, BELGIUM	Hummingbird Collective CommV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	20 Jan 2026	0002099027
Decoster Lukas	10%+ Owner	SQUARE VICTORIA REGAIN 1, SINT-JOOST-TEN-NODE, BELGIUM	HB&Q NV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	20 Jan 2026	0002099021

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	BLLN	Common Stock	Conversion of derivative security		+640,727			640,727	07 Nov 2025	See Footnotes	F1, F2, F3, F8
transaction	BLLN	Common Stock	Conversion of derivative security		+18,845			18,845	07 Nov 2025	See Footnotes	F1, F2, F4, F8
transaction	BLLN	Common Stock	Conversion of derivative security		+2,015,118			2,015,118	07 Nov 2025	See Footnotes	F1, F2, F5, F8
transaction	BLLN	Common Stock	Conversion of derivative security		+2,451,665	+1362%		2,631,664	07 Nov 2025	See Footnotes	F1, F2, F6, F8
transaction	BLLN	Common Stock	Conversion of derivative security		+2,580,833			2,580,833	07 Nov 2025	See Footnotes	F1, F2, F7, F8
transaction	BLLN	Common Stock	Other		-640,727	-100%		0	07 Nov 2025	See Footnotes	F3, F8, F9
transaction	BLLN	Common Stock	Other		-18,845	-100%		0	07 Nov 2025	See Footnotes	F4, F8, F9
transaction	BLLN	Common Stock	Other		-2,015,118	-100%		0	07 Nov 2025	See Footnotes	F5, F8, F9
transaction	BLLN	Common Stock	Other		-2,631,664	-100%		0	07 Nov 2025	See Footnotes	F6, F8, F9
transaction	BLLN	Common Stock	Other		-2,580,833	-100%		0	07 Nov 2025	See Footnotes	F7, F8, F9
transaction	BLLN	Class A Common Stock	Other		+640,727			640,727	07 Nov 2025	See Footnotes	F3, F8, F9
transaction	BLLN	Class A Common Stock	Other		+18,845			18,845	07 Nov 2025	See Footnotes	F4, F8, F9
transaction	BLLN	Class A Common Stock	Other		+2,015,118			2,015,118	07 Nov 2025	See Footnotes	F5, F8, F9
transaction	BLLN	Class A Common Stock	Other		+2,631,664			2,631,664	07 Nov 2025	See Footnotes	F6, F8, F9
transaction	BLLN	Class A Common Stock	Other		+2,580,833			2,580,833	07 Nov 2025	See Footnotes	F7, F8, F9

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 B-2 Convertible Preferred Stock	Conversion of derivative security		-640,727	-100%		0	07 Nov 2025	Common Stock	640,727		See Footnotes	F2, F3, F8
transaction	BLLN	Series B-1 Convertible Preferred Stock	Conversion of derivative security		-18,845	-100%		0	07 Nov 2025	Common Stock	18,845		See Footnotes	F2, F4, F8
transaction	BLLN	Series C Convertible Preferred Stock	Conversion of derivative security		-1,569,015	-100%		0	07 Nov 2025	Common Stock	1,569,015		See Footnotes	F2, F5, F8
transaction	BLLN	Series D Convertible Preferred Stock	Conversion of derivative security		-446,103	-100%		0	07 Nov 2025	Common Stock	446,103		See Footnotes	F2, F5, F8
transaction	BLLN	Series A-1 Convertible Preferred Stock	Conversion of derivative security		-20,000	-100%		0	07 Nov 2025	Common Stock	20,000		See Footnotes	F2, F6, F8
transaction	BLLN	Series A-2 Convertible Preferred Stock	Conversion of derivative security		-33,000	-100%		0	07 Nov 2025	Common Stock	33,000		See Footnotes	F2, F6, F8
transaction	BLLN	Series B-1 Convertible Preferred Stock	Conversion of derivative security		-2,261,377	-100%		0	07 Nov 2025	Common Stock	2,261,377		See Footnotes	F2, F6, F8
transaction	BLLN	Series C Convertible Preferred Stock	Conversion of derivative security		-137,288	-100%		0	07 Nov 2025	Common Stock	137,288		See Footnotes	F2, F6, F8
transaction	BLLN	Series A-6 Convertible Preferred Stock	Conversion of derivative security		-2,260,520	-100%		0	07 Nov 2025	Common Stock	2,260,520		See Footnotes	F2, F7, F8
transaction	BLLN	Series B-2 Convertible Preferred Stock	Conversion of derivative security		-320,363	-100%		0	07 Nov 2025	Common Stock	320,363		See Footnotes	F2, F7, F8

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

Explanation of Responses:

Id	Content
F1	The total represents shares received upon conversion of shares of Series A-1 Convertible Preferred Stock, Series A-2 Convertible Preferred Stock, Series A-6 Convertible Preferred Stock, Series B-1 Convertible Preferred Stock, Series B-2 Convertible Preferred Stock, Series C Convertible Preferred Stock and/or Series D Convertible Preferred Stock.
F2	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.
F3	The reported security is directly held by HB&Q NV (HB&Q COMPARTMENT III).
F4	The reported security is directly held by Hummingbird Collective CommV.
F5	The reported security is directly held by Hummingbird Dragons CommV.
F6	The reported security is directly held by Hummingbird Opportunity Fund II CommV.
F7	The reported security is directly held by Hummingbird Ventures III CommV.
F8	Humming Bird Ventures Management NV is the managing member of Hummingbird Opportunity Fund II CommV, Hummingbird Ventures III CommV, Hummingbird Dragons CommV, Hummingbird Collective CommV, and HB&Q NV (HB&Q COMPARTMENT III) (the Hummingbird Funds) and, as a result, may be deemed to beneficially own shares held by the Hummingbird Funds. Mr. Ileri, Barend Van den Brande, and Lukas Decoster are partners of Hummingbird Ventures Management NV and may be deemed to have shared voting and investment power over the shares held by the Hummingbird Funds. The Reporting Persons disclaim beneficial ownership of these shares except to the extent of their pecuniary interests therein.
F9	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.