Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN 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

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(Print or Type Responses)

1. Name and Address of Reporting Person * KOLLURI KRISHNA KITTU 2. Issuer Name and Ticker or Trading Symbol BillionToOne, Inc. [BLLN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 1300 EL CAMINO REAL, SUITE 100 3. Date of Earliest Transaction (Month/Day/Year) 05/11/2026 (Street) MENLO PARK, CA 94025 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) 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 05/11/2026 J(1) 129,780 D $ 0 1,168,019 I See Footnote(2) Class A Common Stock 05/11/2026 J(3) 7,980 A $ 0 7,980 I See Footnote(4) Class A Common Stock 05/11/2026 J(5) 7,980 D $ 0 0 I See Footnote(4) Class A Common Stock 05/11/2026 J(6) 24,222 D $ 0 217,994 I See Footnote(7) Class A Common Stock 05/11/2026 J(8) 1,425 A $ 0 1,425 I See Footnote(9) Class A Common Stock 05/11/2026 J(10) 1,425 D $ 0 0 I See Footnote(9) Class A Common Stock 05/11/2026 J(11) 271,028 D $ 0 2,439,258 I See Footnote(12) Class A Common Stock 05/11/2026 J(13) 5,423 A $ 0 5,423 I See Footnote(14) Class A Common Stock 05/11/2026 J(15) 5,423 D $ 0 0 I See Footnote(14) Class A Common Stock 05/11/2026 J(16) 10,921 D $ 0 98,283 I See Footnote(17) Class A Common Stock 05/11/2026 J(3) 719 A $ 0 719 I See Footnote(18) Class A Common Stock 05/11/2026 J(3) 719 A $ 0 719 I See Footnote(19) Class A Common Stock 05/11/2026 J(20) 5,761 A $ 0 5,761 I See Footnote(21) Class A Common Stock 05/11/2026 J(22) 1,186 A $ 0 6,947 I See Footnote(21) Class A Common Stock 05/11/2026 J(23) 2,171 A $ 0 9,118 I See Footnote(21) Class A Common Stock 05/11/2026 J(24) 5,644 A $ 0 14,762 I See Footnote(21)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 Underlying Securities (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 of Derivative Security: 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

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
KOLLURI KRISHNA KITTU 1300 EL CAMINO REAL, SUITE 100 MENLO PARK, CA 94025	X	X

Signatures

Krishna Kittu Kolluri, /s/ Krishna Kittu Kolluri		05/13/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	Represents a pro-rata, in-kind distribution by Neotribe Ignite Fund I, L.P. ("NTIF I") to its partners, for no additional consideration.
(2)	The reported security is directly held by NTIF I. Neotribe Ignite Partners I, LLC ("NTIP I") is the general partner of NTIF I. Krishna Kittu Kolluri ("Kolluri") is the managing member of NTIP I and therefore may be deemed to have voting and dispositive power over the shares held by NTIF I. Kolluri disclaims beneficial ownership of the shares held by NTIF I except to the extent of his pecuniary interest therein.
(3)	The shares were obtained pursuant to a pro-rata, in-kind distribution from NTIF I, for no additional consideration.
(4)	The reported security is directly held by NTIP I. Kolluri is the managing member of NTIP I and therefore may be deemed to have voting and dispositive power over the shares held by NTIP I. Kolluri disclaims beneficial ownership of the shares held by NTIP I except to the extent of his pecuniary interest therein.
(5)	Represents a pro-rata, in-kind distribution by NTIP I to its members and assignees, for no additional consideration.
(6)	Represents a pro-rata, in-kind distribution by Neotribe SPV I BTO, LLC ("NT SPV I") to its members, for no additional consideration.
(7)	The reported security is directly held by NT SPV I. Neotribe Partners SPV I BTO, LLC ("NTP SPV I") is the managing member of NT SPV I. Kolluri is the managing member of NTP SPV I and therefore may be deemed to have voting and dispositive power over the shares held by NT SPV I. Kolluri disclaims beneficial ownership of the shares held by NT SPV I except to the extent of his pecuniary interest therein.
(8)	The shares were obtained pursuant to a pro-rata, in-kind distribution from NT SPV I, for no additional consideration.
(9)	The reported security is directly held by NTP SPV I. Kolluri is the managing member of NTP SPV I and therefore may be deemed to have voting and dispositive power over the shares held by NTP SPV I. Kolluri disclaims beneficial ownership of the shares held by NTP SPV I except to the extent of his pecuniary interest therein.
(10)	Represents a pro-rata, in-kind distribution by NTP SPV I to its members and assignees, for no additional consideration.
(11)	Represents a pro-rata, in-kind distribution by NeoTribe Ventures I, L.P. ("NTV I") to its partners, for no additional consideration.
(12)	The reported security is directly held by NTV I, for itself. NeoTribe Partners I, LLC ("NTP I") is the general partner of NTV I. Kolluri is the managing member of NTP I and therefore may be deemed to hold voting and dispositive power over the shares held by NTV I. Kolluri disclaims beneficial ownership of the shares held by NTV I except to the extent of his pecuniary interest therein.
(13)	The shares were obtained pursuant to a pro-rata, in-kind distribution from NTV I, for no additional consideration.
(14)	The reported security is directly held by NTP I. Kolluri is the managing member of NTP I and therefore may be deemed to have voting and dispositive power over the shares held by NTP I. Kolluri disclaims beneficial ownership of the shares held by NTP I except to the extent of his pecuniary interest therein.
(15)	Represents a pro-rata, in-kind distribution by NTP I to its members and assignees, for no additional consideration.
(16)	Represents a pro-rata, in-kind distribution by NeoTribe Associates I, L.P. ("NTA I") to its partners, for no additional consideration.
(17)	The reported security is directly held by NTV I, as nominee for NTA I. NTP I is the general partner of NTA I. Kolluri is the managing member of NTP I and therefore may be deemed to hold voting and dispositive power over the shares held by NTA I. Kolluri disclaims beneficial ownership of the shares held by NTA I except to the extent of his pecuniary interest therein.
(18)	The reported security is directly held by Ishaan S. Kolluri GST Exempt Trust under the Kolluri 2012 Trust Dtd 11/16/2012, of which Kolluri is a trustee and therefore may be deemed to hold voting and dispositive power over these shares. Kolluri disclaims beneficial ownership of these shares.
(19)	The reported security is directly held by Raina V. Kolluri GST Exempt Trust under the Kolluri 2012 Trust Dtd 11/16/2012, of which Kolluri is a trustee and therefore may be deemed to hold voting and dispositive power over these shares. Kolluri disclaims beneficial ownership of these shares.
(20)	The shares were obtained pursuant to a pro-rata, in-kind distribution from NTIP I, for no additional consideration.
(21)	The reported security is directly held by Kolluri Living Trust dated 11/05/1999, of which Kolluri is a trustee and therefore may be deemed to hold voting and dispositive power over these shares. Kolluri disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein.
(22)	The shares were obtained pursuant to a pro-rata, in-kind distribution from NTP SPV I, for no additional consideration.
(23)	The shares were obtained pursuant to a pro-rata, in-kind distribution from NTP I, for no additional consideration.
(24)	The shares were obtained pursuant to a pro-rata, in-kind distribution from NTA I, for no additional consideration.
Remarks: This Form 4 is one of two Form 4s filed in respect of the distribution of these shares held of record by NTIF I, NT SPV I, NTV I and NTA I. The Reporting Person for the other Form 4 is NeoTribe Ventures I, L.P.

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