STOCK TITAN

BillionToOne, Inc. (BLLN) CTO sells 20,000 shares and exercises options

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

BillionToOne, Inc. Chief Technology Officer and director David Tsao reported multiple open-market sales of Class A Common Stock on July 13, 2026, totaling 20,000 shares at weighted-average prices, with underlying trade ranges from $122.185 to $127.2981 per share as detailed in footnotes. He also exercised stock options for 20,000 shares at a $2.8000 exercise price from fully vested options, pursuant to a Rule 10b5-1 trading plan adopted on March 6, 2026.

Positive

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Negative

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Insider Tsao David
Role Chief Technology Officer
Sold 20,000 shs ($2.50M)
Type Security Shares Price Value
Exercise Stock Option (right to buy) 10,000 $2.80 $28K
Exercise Stock Option (right to buy) 10,000 $2.80 $28K
Exercise Class A Common Stock 10,000 $2.80 $28K
Exercise Class A Common Stock 10,000 $2.80 $28K
Sale Class A Common Stock 1,102 $122.9045 $135K
Sale Class A Common Stock 2,477 $123.8435 $307K
Sale Class A Common Stock 2,415 $124.8996 $302K
Sale Class A Common Stock 3,185 $125.8458 $401K
Sale Class A Common Stock 821 $126.888 $104K
Sale Class A Common Stock 1,138 $122.8428 $140K
Sale Class A Common Stock 2,274 $123.7088 $281K
Sale Class A Common Stock 1,725 $124.6538 $215K
Sale Class A Common Stock 3,835 $125.7588 $482K
Sale Class A Common Stock 1,028 $126.8952 $130K
Holdings After Transaction: Stock Option (right to buy) — 610,000 shares (Direct); Class A Common Stock — 11,000 shares (Direct)
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 $122.420 to $123.3775 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 $123.440 to $124.435 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 $124.450 to $125.4325 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 $125.4525 to $126.450 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 $126.490 to $127.2981 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 $122.185 to $123.105 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 $123.2852 to $124.258 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 $124.290 to $125.240 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 $125.295 to $126.2805 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 $126.360 to $127.220 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 options are fully vested and exercisable.
Shares sold 20000 shares Total Class A Common Stock sold on 2026-07-13
Shares from option exercises 20000 shares Class A Common Stock underlying options exercised on 2026-07-13
Reported sale price example 126.8952 per share One weighted-average price for a tranche of Class A shares sold
Lower bound of sale price ranges 122.185 per share Lowest price in weighted-average sale price ranges in footnotes
Upper bound of sale price ranges 127.2981 per share Highest price in weighted-average sale price ranges in footnotes
Option exercise price 2.8000 per share Exercise price for Stock Option (right to buy) expiring 2031-06-07
Stock options outstanding after transaction 610000.0000 shares Shares underlying Stock Option (right to buy) after reported exercises
Rule 10b5-1 trading plan financial
"The 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 titled Stock Option (right to buy) with an exercise price of $2.8000"
derivative security financial
"Exercise or conversion of derivative security is noted in the description"
A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.
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FAQ

What insider transactions did BillionToOne (BLLN) report for David Tsao on July 13, 2026?

On July 13, 2026, CTO David Tsao reported selling 20,000 Class A shares and exercising options for 20,000 shares. The activity combines open-market or private sales with derivative exercises, all disclosed for BillionToOne’s Class A Common Stock.

How many BillionToOne (BLLN) shares did CTO David Tsao sell in this Form 4?

David Tsao reported selling 20,000 shares of BillionToOne Class A Common Stock. These non-derivative sales occurred in multiple tranches on July 13, 2026, at weighted-average prices, with detailed price ranges provided across several footnotes.

At what prices were BillionToOne (BLLN) shares sold by David Tsao?

The reported sales used weighted-average prices, with underlying trades ranging from $122.185 to $127.2981 per share. Each tranche’s prices are disclosed in footnotes, which specify the exact price intervals for the multiple transactions within those ranges.

What stock options did David Tsao exercise in BillionToOne (BLLN)?

David Tsao exercised options for 20,000 shares of Class A Common Stock at an exercise price of $2.8000 per share. The options, described as fully vested and exercisable, are Stock Options (right to buy) expiring on June 7, 2031.

Was the BillionToOne (BLLN) insider trading activity under a Rule 10b5-1 plan?

Yes. The filing states the transactions were effected under a Rule 10b5-1 trading plan adopted on March 6, 2026. Such pre-arranged plans systematically schedule trades, which can reduce the significance of timing for interpreting insider intent.

How many stock options remain after David Tsao’s BillionToOne (BLLN) transactions?

After the reported option exercises, one Stock Option (right to buy) position shows 610,000.0000 shares underlying options. This figure appears as the total shares following transaction for the derivative security on July 13, 2026.
SEC Form 4
FORM 4UNITED 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*
Tsao David

(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)
XDirector10% Owner
XOfficer (give title below)Other (specify below)
Chief Technology Officer
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
07/13/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Class A Common Stock07/13/2026M(1)10,000A$2.811,000D
Class A Common Stock07/13/2026M(1)10,000A$2.821,000D
Class A Common Stock07/13/2026S(1)1,102D$122.9045(2)19,898D
Class A Common Stock07/13/2026S(1)2,477D$123.8435(3)17,421D
Class A Common Stock07/13/2026S(1)2,415D$124.8996(4)15,006D
Class A Common Stock07/13/2026S(1)3,185D$125.8458(5)11,821D
Class A Common Stock07/13/2026S(1)821D$126.888(6)11,000D
Class A Common Stock07/13/2026S(1)1,138D$122.8428(7)9,862D
Class A Common Stock07/13/2026S(1)2,274D$123.7088(8)7,588D
Class A Common Stock07/13/2026S(1)1,725D$124.6538(9)5,863D
Class A Common Stock07/13/2026S(1)3,835D$125.7588(10)2,028D
Class A Common Stock07/13/2026S(1)1,028D$126.8952(11)1,000D
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Stock Option (right to buy)$2.807/13/2026M10,000 (12)06/07/2031Class A Common Stock10,000$2.8610,000D
Stock Option (right to buy)$2.807/13/2026M10,000 (12)06/07/2031Class A Common Stock10,000$2.8600,000D
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 $122.420 to $123.3775 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 $123.440 to $124.435 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 $124.450 to $125.4325 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 $125.4525 to $126.450 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 $126.490 to $127.2981 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 $122.185 to $123.105 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 $123.2852 to $124.258 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 $124.290 to $125.240 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 $125.295 to $126.2805 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 $126.360 to $127.220 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.
12. The options are fully vested and exercisable.
Remarks:
/s/ Thomas P. Lynch, Attorney-in-Fact07/15/2026
** Signature of Reporting PersonDate
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)