What are the reported BillionToOne (BLLN) share holdings after the insider sales?

After the reported sales, the Form 4 shows 34,968 shares owned directly following one transaction and 36,384 shares following another. Both entries relate to Class A Common Stock and reflect direct ownership positions after the June 15, 2026 trades.

BillionToOne (BLLN) officer sells 2,832 shares under Rule 10b5-1 plan

Filing Impact

(Moderate)

Filing Sentiment

(Negative)

Form Type

Rhea-AI Filing Summary

BillionToOne, Inc. officer ten Bosch John Roderick reported selling a total of 2,832 shares of Class A Common Stock in open-market transactions. The sales were executed at a price of $101.47 per share on June 15, 2026. Following these transactions, the filing shows direct holdings of 34,968 shares after one sale and 36,384 shares after another. According to a footnote, the trades were made under a pre-arranged Rule 10b5-1 trading plan adopted on March 6, 2026, indicating they were scheduled in advance rather than timed discretionarily.

Insider Trade Summary 10b5-1

Net Seller: 2,832 shares ($287,363)

Net Sell 2 txns

Insider ten Bosch John Roderick

Role See Remarks

Sold 2,832 shs ($287K)

Type	Security	Shares	Price	Value
Sale	Class A Common Stock	1,416	$101.47	$144K
Sale	Class A Common Stock	1,416	$101.47	$144K

Holdings After Transaction: Class A Common Stock — 36,384 shares (Direct, null)

Footnotes (1)

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Key Figures

Shares sold: 2,832 shares Sale price: $101.47 per share Holdings after sale (entry 1): 34,968 shares +2 more

5 metrics

Shares sold 2,832 shares Total Class A Common Stock sold on June 15, 2026

Sale price $101.47 per share Open-market sale price on June 15, 2026

Holdings after sale (entry 1) 34,968 shares Direct Class A Common Stock holding after one reported sale

Holdings after sale (entry 2) 36,384 shares Direct Class A Common Stock holding after another reported sale

Rule 10b5-1 plan adoption date March 6, 2026 Date the pre-arranged trading plan was adopted

Key Terms

Rule 10b5-1 trading plan, open-market sale, Class A Common Stock, non-derivative

4 terms

Rule 10b5-1 trading plan regulatory

"The transactions reported on this Form 4 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.

open-market sale financial

"transaction_action": "open-market sale""

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

Class A Common Stock financial

""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.

non-derivative financial

""transaction_type": "non-derivative""

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Form 4 Insider Transactions: What Each Field Means →

06/17/2026 - 05:47 PM

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^*

ten Bosch John Roderick

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/15/2026

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	06/15/2026		S⁽¹⁾		1,416	D	$101.47	36,384	D
Class A Common Stock	06/15/2026		S⁽¹⁾		1,416	D	$101.47	34,968	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)
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)

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.

Remarks:

Senior Vice President of Laboratory Operations

	/s/ Thomas P. Lynch, Attorney-in-Fact	06/17/2026
	** 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

FAQ

What insider activity did BillionToOne (BLLN) report in this Form 4?

BillionToOne reported that officer ten Bosch John Roderick sold 2,832 shares of Class A Common Stock in open-market transactions. The sales occurred on June 15, 2026 at a price of $101.47 per share under a pre-arranged Rule 10b5-1 trading plan.

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

The insider sold 2,832 shares of BillionToOne Class A Common Stock at $101.47 per share. The transactions were coded as open-market sales and were executed on June 15, 2026, according to the Form 4 filing details provided.

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

Yes. A footnote states the transactions were effected under a Rule 10b5-1 trading plan adopted on March 6, 2026. Such pre-arranged plans schedule trades in advance, so the timing of these June 15, 2026 sales was determined before execution.

What do the transaction codes mean in the BillionToOne (BLLN) Form 4?

Each transaction is marked with code “S,” indicating a sale in an open-market or private transaction. The filing also labels them as non-derivative transactions in Class A Common Stock, rather than option exercises or other derivative-related activity.