BillionToOne (NASDAQ: BLLN) officer sells 14,000 shares under 10b5-1 plan

Rhea-AI Filing Summary

BillionToOne, Inc. officer Nancy JoAnn Johnson reported open-market sales of 14,000 shares of Class A Common Stock on June 8–9, 2026. The shares were sold in seven transactions at weighted-average prices generally around $99–$102 per share, under a pre-arranged Rule 10b5-1 trading plan adopted on March 6, 2026.

Insights

Equity analyst

Routine 10b5-1 insider sales totaling 14,000 shares, with limited signal value.

Insider Nancy JoAnn Johnson sold an aggregate 14,000 shares of BillionToOne, Inc. Class A Common Stock in seven open-market transactions on June 8–9, 2026. Reported weighted-average prices ranged from about $98.900 to $102.570 per share.

The filing states the trades were executed under a pre-arranged Rule 10b5-1 trading plan adopted on March 6, 2026. Such plans are set up in advance, so the timing of these sales generally carries less informational weight about the insider’s short-term view of the stock.

No derivative exercises or awards are reported, and the derivativeSummary is empty, indicating this Form 4 only covers common stock sales rather than option activity. Future company filings may provide broader context on Johnson’s overall equity compensation and holdings.

Insider Trade Summary 10b5-1

Net Seller: 14,000 shares ($1,402,540)

Net Sell 7 txns

Insider Johnson Nancy JoAnn

Role See Remarks

Sold 14,000 shs ($1.40M)

Type	Security	Shares	Price	Value
Sale	Class A Common Stock	4,666	$99.2721	$463K
Sale	Class A Common Stock	2,700	$101.3757	$274K
Sale	Class A Common Stock	1,816	$102.3367	$186K
Sale	Class A Common Stock	1,400	$100.3079	$140K
Sale	Class A Common Stock	2,918	$99.0868	$289K
Sale	Class A Common Stock	300	$100.05	$30K
Sale	Class A Common Stock	200	$100.985	$20K

Holdings After Transaction: Class A Common Stock — 27,816 shares (Direct, null)

Footnotes (1)

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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $98.900 to $99.690 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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $99.960 to $100.220 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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $100.980 to $100.990 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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $98.900 to $99.870 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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $100.990 to $101.710 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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $101.990 to $102.570 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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $99.990 to $100.720 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.

Key Figures

Shares sold: 14,000 shares Lowest price range: $98.900/share Highest price range: $102.570/share +2 more

5 metrics

Shares sold 14,000 shares Aggregate insider sales on June 8–9, 2026

Lowest price range $98.900/share Lower end of weighted-average trade ranges in footnotes

Highest price range $102.570/share Upper end of weighted-average trade ranges in footnotes

Number of sell transactions 7 sales transactionSummary sellCount

10b5-1 plan adoption date March 6, 2026 Footnote indicating pre-arranged trading plan

Key Terms

Rule 10b5-1 trading plan, weighted average price, Class A Common Stock, open-market sale

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.

weighted average price financial

"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions..."

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.

Class A Common Stock financial

"security_title: Class A Common Stock for each non-derivative transaction listed"

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.

open-market sale financial

"transaction_action: open-market sale for each reported non-derivative transaction"

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.

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Form 4 Insider Transactions: What Each Field Means →

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^*

Johnson Nancy JoAnn

(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)
06/08/2026

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	06/08/2026		S(1)		2,918	D	$99.0868(2)	32,982	D
Class A Common Stock	06/08/2026		S(1)		300	D	$100.05(3)	32,682	D
Class A Common Stock	06/08/2026		S(1)		200	D	$100.985(4)	32,482	D
Class A Common Stock	06/09/2026		S(1)		4,666	D	$99.2721(5)	27,816	D
Class A Common Stock	06/09/2026		S(1)		2,700	D	$101.3757(6)	25,116	D
Class A Common Stock	06/09/2026		S(1)		1,816	D	$102.3367(7)	23,300	D
Class A Common Stock	06/09/2026		S(1)		1,400	D	$100.3079(8)	21,900	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

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 $98.900 to $99.690 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 $99.960 to $100.220 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 $100.980 to $100.990 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 $98.900 to $99.870 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 $100.990 to $101.710 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 $101.990 to $102.570 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 $99.990 to $100.720 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.

Remarks:

Senior Vice President of Sales and Commercial Operations

	/s/ Thomas P. Lynch, Attorney-in-Fact	06/10/2026
	** 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)

FAQ

How many BillionToOne (BLLN) shares did Nancy JoAnn Johnson sell?

Nancy JoAnn Johnson sold a total of 14,000 shares of BillionToOne Class A Common Stock. The Form 4 summarizes seven open-market sales reported over June 8–9, 2026, all classified as non-derivative transactions in common stock.

At what prices were the BLLN insider sales by Nancy JoAnn Johnson executed?

The reported sales used weighted average prices for each transaction. Footnotes state individual trades occurred in ranges from about $98.900 to $102.570 per share, with the insider offering to provide exact breakdowns upon written request.

Were Nancy JoAnn Johnson’s BLLN share sales under a Rule 10b5-1 plan?

Yes. A footnote explains the transactions were effected under a Rule 10b5-1 trading plan adopted by Nancy JoAnn Johnson on March 6, 2026. Such pre-arranged plans typically reduce the significance of trade timing as a market signal.

Did the BillionToOne (BLLN) Form 4 include any option exercises or derivatives?

No derivative activity is reported in this Form 4. All seven transactions involve non-derivative Class A Common Stock, and the filing’s derivativeSummary section is empty, indicating no option exercises, conversions, or other derivative trades were disclosed here.

How many insider transactions did BillionToOne (BLLN) report for Nancy JoAnn Johnson?

The transactionSummary shows seven sell transactions and no buys or exercises. Each entry reflects an open-market sale of Class A Common Stock, contributing to a total of 14,000 shares sold over the two-day period covered.