BillionToOne CEO, spouse sell 30,335 shares

Q: How many BLLN shares did Oguzhan Atay report selling?

The transaction summary records sales of 30,335 Class A shares on November 2, 2026, with reported prices ranging from $107.3142 to $113.1700 per share. Atay's transactions were under a Rule 10b5-1 plan adopted June 5, 2026; his spouse's reported sales were under a separate plan adopted June 7, 2026.

Q: How many options did BLLN's CEO exercise, and at what price?

Oguzhan Atay exercised options covering 25,001 Class A shares at $2.80 per share on November 2, 2026. The options were fully vested and exercisable, and their stated expiration date was June 7, 2031.

Atay's transactions were reported under a Rule 10b5-1 plan adopted June 5, 2026; his spouse's sales were under a separate plan adopted June 7, 2026.

Available on EDGAR 11/04/2026 - 08:47 PM EST Accepted by SEC EDGAR 11/04/2026 - 08:42 PM EST

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Rhea-AI Filing Summary

BillionToOne, Inc. (BLLN) Chairman and CEO Oguzhan Atay exercised options covering 25,001 Class A shares at $2.80 per share on November 2, 2026. The transaction summary records sales of 30,335 Class A shares that day, including shares reported as held by his spouse; reported sale prices ranged from $107.3142 to $113.1700 per share. Atay's transactions were effected under a Rule 10b5-1 trading plan adopted June 5, 2026, and his spouse's sales under a separate plan adopted June 7, 2026.

Insider Trade Summary 10b5-1

Exercise and sale activity reported; no spread calculated

Exercise and Sale 18 txns

Insider Atay Oguzhan

Role Chairman and CEO

Sold 30,335 shs ($3.33M)

Approx. gross sale proceeds $3.33M

Approx. exercise cost $70K

Type	Security	Shares	Price	Value
Exercise	Stock Option (right to buy) ^F16	16,667	$2.80	$47K
Exercise	Stock Option (right to buy) ^F16	8,334	$2.80	$23K
Exercise	Class A Common Stock ^F1	16,667	$2.80	$47K
Exercise	Class A Common Stock ^F1	8,334	$2.80	$23K
Sale	Class A Common Stock ^{F1, F2}	1,482	$107.3142	$159K
Sale	Class A Common Stock ^{F1, F3}	4,009	$108.2464	$434K
Sale	Class A Common Stock ^{F1, F4}	5,720	$109.0791	$624K
Sale	Class A Common Stock ^{F1, F5}	3,803	$110.29	$419K
Sale	Class A Common Stock ^{F1, F6}	1,117	$110.9784	$124K
Sale	Class A Common Stock ^{F1, F7}	536	$112.4416	$60K
Sale	Class A Common Stock ^{F1, F8}	974	$107.3386	$105K
Sale	Class A Common Stock ^{F1, F9}	2,075	$108.429	$225K
Sale	Class A Common Stock ^{F1, F10}	2,451	$109.1145	$267K
Sale	Class A Common Stock ^{F1, F11}	2,223	$110.3508	$245K
Sale	Class A Common Stock ^{F1, F12}	411	$111.0265	$46K
Sale	Class A Common Stock ^{F1, F13}	200	$112.39	$22K
Sale	Class A Common Stock ^{F14, F15}	2,667	$113.17	$302K
Sale	Class A Common Stock ^{F14, F15}	2,667	$113.17	$302K

Holdings After Transaction: Stock Option (right to buy) — 435,295 contracts (Direct); Class A Common Stock — 0 shares (Direct); Class A Common Stock — 141,167 shares (Indirect, By spouse)

Footnotes (16)

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 5, 2026.
F2. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $106.620 to $107.600 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F3. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $107.635 to $108.630 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F4. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $108.675 to $109.555 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F5. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $109.760 to $110.7425 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F6. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $110.780 to $111.650 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F7. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $111.950 to $112.820 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F8. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $106.700 to $107.660 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F9. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $107.785 to $108.7772 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F10. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $108.790 to $109.760 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F11. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $109.800 to $110.790 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F12. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $110.825 to $111.535 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F13. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $111.950 to $112.830 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
F14. The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person's spouse on June 7, 2026.
F15. Represents shares held by the Reporting Person's spouse.
F16. The options are fully vested and exercisable.

Key Figures

Shares sold: 30,335 shares Options exercised: 25,001 shares Exercise price: $2.80 per share +1 more

4 metrics

Shares sold 30,335 shares Transaction summary; November 2, 2026

Options exercised 25,001 shares November 2, 2026

Exercise price $2.80 per share Options exercised November 2, 2026

Reported sale prices $107.3142–$113.1700 per share Sale entries dated November 2, 2026

Key Terms

Rule 10b5-1 trading plan, weighted average price, fully vested and exercisable

3 terms

Rule 10b5-1 trading plan regulatory

"transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan"

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.

weighted average price financial

"The reported price in Column 4 is a weighted average price"

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

fully vested and exercisable technical

"The options are fully vested and exercisable"

FAQ

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

How many BLLN shares did Oguzhan Atay report selling?

The transaction summary records sales of 30,335 Class A shares on November 2, 2026, with reported prices ranging from $107.3142 to $113.1700 per share. Atay's transactions were under a Rule 10b5-1 plan adopted June 5, 2026; his spouse's reported sales were under a separate plan adopted June 7, 2026.

How many options did BLLN's CEO exercise, and at what price?

Oguzhan Atay exercised options covering 25,001 Class A shares at $2.80 per share on November 2, 2026. The options were fully vested and exercisable, and their stated expiration date was June 7, 2031.

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

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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).

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^*

Atay Oguzhan

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
11/02/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Class A Common Stock	11/02/2026		M⁽¹⁾		16,667	A	$2.8	16,667	D
Class A Common Stock	11/02/2026		M⁽¹⁾		8,334	A	$2.8	25,001	D
Class A Common Stock	11/02/2026		S⁽¹⁾		1,482	D	$107.3142⁽²⁾	23,519	D
Class A Common Stock	11/02/2026		S⁽¹⁾		4,009	D	$108.2464⁽³⁾	19,510	D
Class A Common Stock	11/02/2026		S⁽¹⁾		5,720	D	$109.0791⁽⁴⁾	13,790	D
Class A Common Stock	11/02/2026		S⁽¹⁾		3,803	D	$110.29⁽⁵⁾	9,987	D
Class A Common Stock	11/02/2026		S⁽¹⁾		1,117	D	$110.9784⁽⁶⁾	8,870	D
Class A Common Stock	11/02/2026		S⁽¹⁾		536	D	$112.4416⁽⁷⁾	8,334	D
Class A Common Stock	11/02/2026		S⁽¹⁾		974	D	$107.3386⁽⁸⁾	7,360	D
Class A Common Stock	11/02/2026		S⁽¹⁾		2,075	D	$108.429⁽⁹⁾	5,285	D
Class A Common Stock	11/02/2026		S⁽¹⁾		2,451	D	$109.1145⁽¹⁰⁾	2,834	D
Class A Common Stock	11/02/2026		S⁽¹⁾		2,223	D	$110.3508⁽¹¹⁾	611	D
Class A Common Stock	11/02/2026		S⁽¹⁾		411	D	$111.0265⁽¹²⁾	200	D
Class A Common Stock	11/02/2026		S⁽¹⁾		200	D	$112.39⁽¹³⁾	0	D
Class A Common Stock	11/02/2026		S⁽¹⁴⁾		2,667	D	$113.17	143,834	I	By spouse⁽¹⁵⁾
Class A Common Stock	11/02/2026		S⁽¹⁴⁾		2,667	D	$113.17	141,167	I	By spouse⁽¹⁵⁾

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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (right to buy)	$2.8	11/02/2026		M			16,667	⁽¹⁶⁾	06/07/2031	Class A Common Stock	16,667	$2.8	443,629	D
Stock Option (right to buy)	$2.8	11/02/2026		M			8,334	⁽¹⁶⁾	06/07/2031	Class A Common Stock	8,334	$2.8	435,295	D

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 5, 2026.

2. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $106.620 to $107.600 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

3. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $107.635 to $108.630 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

4. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $108.675 to $109.555 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

5. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $109.760 to $110.7425 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

6. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $110.780 to $111.650 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

7. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $111.950 to $112.820 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

8. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $106.700 to $107.660 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

9. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $107.785 to $108.7772 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

10. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $108.790 to $109.760 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

11. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $109.800 to $110.790 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

12. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $110.825 to $111.535 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

13. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $111.950 to $112.830 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

14. The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person's spouse on June 7, 2026.

15. Represents shares held by the Reporting Person's spouse.

16. The options are fully vested and exercisable.

Remarks:

	/s/ Thomas P. Lynch, Attorney-in-Fact	11/04/2026
	** 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)

Source: View Original Filing on SEC EDGAR