BillionToOne CEO exercises options, sells shares

BillionToOne, Inc. Chairman and CEO Atay Oguzhan exercised stock options to acquire 15,539 shares of Class A Common Stock at $2.80 per share, then sold 15,539 shares at a weighted average of $150.0323 per share.

Rhea-AI Filing Summary

BillionToOne, Inc. Chairman and CEO Atay Oguzhan exercised stock options to acquire 15,539 shares of Class A Common Stock at $2.80 per share, then sold 15,539 shares at a weighted average of $150.0323 per share. The options were fully vested and exercisable, leaving 526,961 stock options outstanding. All reported transactions were effected under a Rule 10b5-1 trading plan adopted on March 6, 2026.

Insider Trade Summary 10b5-1

Exercise and Sale: 15,539 shares ($2.29M approx. pre-tax spread)

Exercise and Sale 3 txns

Insider Atay Oguzhan

Role Chairman and CEO

Sold 15,539 shs ($2.33M)

Approx. gross sale proceeds $2.33M

Approx. exercise cost $44K

Approx. pre-tax spread $2.29M

Type	Security	Shares	Price	Value
Exercise	Stock Option (right to buy) F3	15,539	$2.80	$44K
Exercise	Class A Common Stock	15,539	$2.80	$44K
Sale	Class A Common Stock F1, F2	15,539	$150.0323	$2.33M

Holdings After Transaction: Stock Option (right to buy) — 526,961 contracts (Direct); Class A Common Stock — 0 shares (Direct)

Footnotes (3)

1. F1. The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 6, 2026.
2. F2. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $150.000 to $150.260 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. F3. The options are fully vested and exercisable.

Key Figures

Options exercised: 15,539 shares Exercise price: $2.80 per share Shares sold: 15,539 shares +2 more

5 metrics

Options exercised 15,539 shares Stock options converted into Class A Common Stock on 2026-08-05

Exercise price $2.80 per share Exercise or conversion price of stock options

Shares sold 15,539 shares Class A Common Stock sale on 2026-08-05

Weighted average sale price $150.0323 per share Weighted average for sales, range $150.000–$150.260 per share

Options remaining 526,961 options Stock options reported as beneficially owned after the exercise

Key Terms

Rule 10b5-1 trading plan, weighted average price, Stock Option (right to buy), Class A Common Stock

4 terms

Rule 10b5-1 trading plan regulatory

"transactions were effected pursuant to a Rule 10b5-1 trading plan adopted"

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.

Stock Option (right to buy) financial

"security_title: Stock Option (right to buy)"

Class A Common Stock financial

"underlying_security_title: Class A Common Stock"

Class A common stock is a category of a company’s shares that carries a specific set of ownership rights—most commonly defined voting power and claims on dividends—set out in the company’s charter. For investors it matters because the class determines how much influence you have over corporate decisions, the share’s likely dividend and trading behavior, and how it compares in value to other share classes, like choosing a particular seat with different privileges at the company’s decision-making table.

FAQ

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

What insider transactions did BillionToOne (BLLN) CEO Atay Oguzhan report?

Atay Oguzhan reported exercising stock options for 15,539 shares of Class A Common Stock at $2.80 per share and then selling 15,539 shares at a weighted average of $150.0323 per share, all on August 5, 2026, under a Rule 10b5-1 plan.

How many BillionToOne (BLLN) shares did the CEO sell and at what price?

The CEO sold 15,539 shares of BillionToOne Class A Common Stock at a weighted average price of $150.0323 per share. The sales occurred in multiple transactions, with prices ranging from $150.000 to $150.260 per share, as disclosed in the filing footnote.

Were the BillionToOne (BLLN) insider transactions made under a Rule 10b5-1 trading plan?

Yes. The filing states that all transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 6, 2026. The document-level Rule 10b5-1 checkbox is also marked, confirming plan-based trading for these transactions.

What options does the BillionToOne (BLLN) CEO hold after these transactions?

After exercising some options, the CEO is reported as beneficially owning 526,961 stock options. These are listed as Stock Option (right to buy) positions, separate from any common stock holdings, and represent options remaining after the 15,539-share exercise on August 5, 2026.

What was the exercise price for the BillionToOne (BLLN) stock options?

The exercised stock options had a conversion or exercise price of $2.80 per share. They were described as fully vested and exercisable, and the exercise converted the options into 15,539 shares of Class A Common Stock before those shares were sold the same day.

What price range applied to the BillionToOne (BLLN) share sales?

The weighted average sale price was $150.0323 per share, with individual trades executed between $150.000 and $150.260 per share. The reporting holder has undertaken to provide full details of the number of shares sold at each separate price upon written request.

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

Form 4 Insider Transactions: What Each Field Means →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 08/07/2026 - 04:03 PM Accepted by SEC EDGAR 08/07/2026 - 04:02 PM Learn about SEC filing dates

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).

X

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)
08/05/2026

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)
			Code	V	Amount	(A) or (D)	Price
Class A Common Stock	08/05/2026		M		15,539	A	$2.8	15,539	D
Class A Common Stock	08/05/2026		S(1)		15,539	D	$150.0323(2)	0	D

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (right to buy)	$2.8	08/05/2026		M			15,539	(3)	06/07/2031	Class A Common Stock	15,539	$2.8	526,961	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 March 6, 2026.

2. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $150.000 to $150.260 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 options are fully vested and exercisable.

Remarks:

	/s/ Thomas P. Lynch, Attorney-in-Fact	08/07/2026
	** 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)