Hummingbird funds disclose BillionToOne (BLLN) pre-IPO ownership stake

Rhea-AI Filing Summary

BillionToOne, Inc. filed an initial ownership report showing that several Hummingbird investment vehicles are 10% owners as of 11/05/2025. The filing reports indirect beneficial ownership of 179,999 shares of Common Stock and multiple series of convertible preferred stock, all held through Hummingbird funds. These preferred shares are convertible into Common Stock on a one-for-one basis and will automatically convert into Class A common stock immediately prior to the company’s initial public offering without additional payment. Humming Bird Ventures Management NV is the managing member of the Hummingbird funds and, along with certain partners, may be deemed to share voting and investment power, while the reporting persons disclaim beneficial ownership beyond their pecuniary interests.

SEC Form 3

FORM 3

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

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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:			3235-0104
Estimated average burden
hours per response:			0.5

1. Name and Address of Reporting Person^*

Humming Bird Ventures Management NV

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
11/05/2025

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

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

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

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

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

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

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock(1)	179,999	I	See footnotes(2)(8)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series B-2 Convertible Preferred Stock	(3)	(3)	Common Stock(1)	640,727	(3)	I	See footnotes(4)(8)
Series B-1 Convertible Preferred Stock	(3)	(3)	Common Stock(1)	18,845	(3)	I	See footnotes(5)(8)
Series C Convertible Preferred Stock	(3)	(3)	Common Stock(1)	1,569,015	(3)	I	See footnotes(6)(8)
Series D Convertible Preferred Stock	(3)	(3)	Common Stock(1)	446,103	(3)	I	See footnotes(6)(8)
Series A-1 Convertible Preferred Stock	(3)	(3)	Common Stock(1)	20,000	(3)	I	See footnotes(2)(8)
Series A-2 Convertible Preferred Stock	(3)	(3)	Common Stock(1)	33,000	(3)	I	See footnotes(2)(8)
Series B-1 Convertible Preferred Stock	(3)	(3)	Common Stock(1)	2,261,377	(3)	I	See footnotes(2)(8)
Series C Convertible Preferred Stock	(3)	(3)	Common Stock(1)	137,288	(3)	I	See footnotes(2)(8)
Series A-6 Convertible Preferred Stock	(3)	(3)	Common Stock(1)	2,260,520	(3)	I	See footnotes(7)(8)
Series B-2 Convertible Preferred Stock	(3)	(3)	Common Stock(1)	320,363	(3)	I	See footnotes(7)(8)

1. Name and Address of Reporting Person^*

Humming Bird Ventures Management NV

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Hummingbird Opportunity Fund II CommV

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Hummingbird Ventures III CommV

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Hummingbird Dragons CommV

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Hummingbird Collective CommV

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

HB&Q NV (HB&Q COMPARTMENT III)

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Van den Brande Barend

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Decoster Lukas

(Last) (First) (Middle)

SQUARE VICTORIA REGAIN 1

(Street)

SINT-JOOST-TEN-NODE C9 1210

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. Immediately prior to the completion of the Issuer's initial public offering of Class A common stock (the "Offering"), each share of Common Stock shall be reclassified into one share of Class A common stock.

2. The reported security is directly held by Hummingbird Opportunity Fund II CommV.

3. The reported security is convertible into the Issuer's Common Stock on a one-for-one basis at any time at the holder's election and shall automatically convert into Class A common stock immediately prior to the closing of the Offering without payment of further consideration. The shares have no expiration date.

4. The reported security is directly held by HB&Q NV (HB&Q COMPARTMENT III).

5. The reported security is directly held by Hummingbird Collective CommV.

6. The reported security is directly held by Hummingbird Dragons CommV.

7. The reported security is directly held by Hummingbird Ventures III CommV.

8. 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. Firat 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.

	Hummingbird Ventures Management NV /s/ Lukas Decoster 49/9 CommV, represented by its permanent representative Lukas Decoster, Director	01/20/2026
	/s/ Barend Van den Brande	01/20/2026
	/s/ Lukas Decoster	01/20/2026
	Hummingbird Opportunity Fund II CommV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	01/20/2026
	Hummingbird Ventures III CommV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	01/20/2026
	Hummingbird Dragons CommV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	01/20/2026
	Hummingbird Collective CommV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	01/20/2026
	HB&Q NV /s/ Firat Ileri By: Hummingbird Ventures Management NV, its Manager By: Firat Ileri, Permanent Representative	01/20/2026
	** 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 5 (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.

FAQ

What did BillionToOne (BLLN) disclose in this Form 3?

BillionToOne, Inc. disclosed initial beneficial ownership positions for several Hummingbird investment entities that are 10% owners, detailing their indirect holdings of Common Stock and multiple series of convertible preferred stock.

Which Hummingbird entities are reported as 10% owners of BillionToOne (BLLN)?

The filing lists Humming Bird Ventures Management NV, Hummingbird Opportunity Fund II CommV, Hummingbird Ventures III CommV, Hummingbird Dragons CommV, Hummingbird Collective CommV, and HB&Q NV (HB&Q COMPARTMENT III) as 10% owners.

How many shares of BillionToOne common stock are indirectly held by the Hummingbird funds?

The report shows indirect beneficial ownership of 179,999 shares of Common Stock, in addition to multiple series of convertible preferred stock that are exchangeable into Common Stock.

How do the Hummingbird preferred shares in BillionToOne (BLLN) convert?

The Series A-1, A-2, A-6, B-1, B-2, C, and D convertible preferred shares are each convertible into the issuer’s Common Stock on a one-for-one basis and will automatically convert into Class A common stock immediately prior to the closing of the initial public offering without further consideration.

Did this BillionToOne Form 3 show any insider buying or selling?

No. The entries are classified as holdings, indicating positions as of 11/05/2025, rather than new purchases or sales.

What role does Humming Bird Ventures Management NV play in these BillionToOne holdings?

Humming Bird Ventures Management NV is the managing member of the Hummingbird funds that directly hold the securities and may be deemed to beneficially own those shares, while the reporting persons disclaim beneficial ownership except to the extent of their pecuniary interests.