STOCK TITAN

BillionToOne (BLLN) CPO sells 8,000 shares and exercises options in pre-set plan

Filing Impact
(Very High)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

BillionToOne, Inc. Chief Product Officer Shan Riku Sakakibara reported open‑market sales of Class A Common Stock totaling 8,000 shares at $125.00 per share on July 9, 2026. On the same date, Sakakibara exercised stock options for 4,000 shares of Class A Common Stock at exercise prices of $30.78 and $8.65 per share. The company notes these trades were effected under a Rule 10b5‑1 trading plan and that the options exercised were fully vested and exercisable.

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Insider Sakakibara Shan Riku
Role Chief Product Officer
Sold 8,000 shs ($1.00M)
Type Security Shares Price Value
Exercise Stock Option (right to buy) 174 $8.65 $2K
Exercise Stock Option (right to buy) 1,117 $30.78 $34K
Exercise Stock Option (right to buy) 1,355 $30.78 $42K
Exercise Stock Option (right to buy) 1,354 $30.78 $42K
Exercise Class A Common Stock 174 $8.65 $2K
Exercise Class A Common Stock 1,117 $30.78 $34K
Exercise Class A Common Stock 1,355 $30.78 $42K
Exercise Class A Common Stock 1,354 $30.78 $42K
Sale Class A Common Stock 4,000 $125.00 $500K
Sale Class A Common Stock 174 $125.00 $22K
Sale Class A Common Stock 1,117 $125.00 $140K
Sale Class A Common Stock 1,355 $125.00 $169K
Sale Class A Common Stock 1,354 $125.00 $169K
Holdings After Transaction: Stock Option (right to buy) — 35,826 shares (Direct); Class A Common Stock — 208,174 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 options are fully vested and exercisable. The terms of the underlying option grant are as previously reported on the Reporting Person's Form 3 filed on November 5, 2025.
Shares sold 8,000 shares Total Class A Common Stock sold in open-market transactions on July 9, 2026
Sale price $125.00 per share Price for each reported Class A Common Stock sale transaction
Options exercised 4,000 shares Total Class A shares underlying options exercised on July 9, 2026
Option exercise price $30.78 per share Exercise price for several Stock Option (right to buy) tranches
Lower exercise price $8.65 per share Exercise price for one Stock Option (right to buy) tranche
Exercise transactions 4 exercises Number of derivative exercises (M code) reported in transaction summary
Net share change (buy/sell) -8,000 shares Net buy/sell shares across reported non-derivative transactions
Rule 10b5-1 trading plan regulatory
"The transactions reported ... 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.
Stock Option (right to buy) financial
"security_title: Stock Option (right to buy) ... underlying security: Class A"
derivative security financial
"transaction_code_description: Exercise or conversion of derivative security"
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.
fully vested and exercisable financial
"The options are fully vested and exercisable. The terms of the underlying"
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FAQ

What insider transactions did BLLN’s Chief Product Officer report on July 9, 2026?

The Chief Product Officer reported selling 8,000 Class A shares at $125.00 and exercising options for 4,000 shares at $30.78 and $8.65 per share, all on July 9, 2026.

Were the BLLN insider stock sales by Shan Riku Sakakibara pre-planned?

Yes. The filing states the transactions were effected under a Rule 10b5‑1 trading plan adopted on March 6, 2026, indicating the trades were pre‑scheduled rather than discretionary market‑timing decisions.

How many BLLN shares did the Chief Product Officer sell and at what price?

Sakakibara sold a total of 8,000 shares of BillionToOne Class A Common Stock at an average price of $125.00 per share, through multiple open‑market sale transactions reported for July 9, 2026.

What stock options did the BLLN insider exercise in this Form 4?

The insider exercised options covering 4,000 shares of Class A Common Stock, including tranches at a $30.78 exercise price and a tranche at $8.65 per share. The filing notes these options were fully vested and exercisable.

What does the Rule 10b5-1 plan mean for these BLLN insider trades?

The filing explains the trades occurred under a Rule 10b5‑1 trading plan, meaning quantities and timing were set in advance on March 6, 2026, reducing the significance of short‑term market conditions in interpreting these transactions.
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*
Sakakibara Shan Riku

(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)
Director10% Owner
XOfficer (give title below)Other (specify below)
Chief Product Officer
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
07/09/2026
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 Stock07/09/2026M(1)174A$8.65208,174D
Class A Common Stock07/09/2026M(1)1,117A$30.78209,291D
Class A Common Stock07/09/2026M(1)1,355A$30.78210,646D
Class A Common Stock07/09/2026M(1)1,354A$30.78212,000D
Class A Common Stock07/09/2026S(1)4,000D$125208,000D
Class A Common Stock07/09/2026S(1)174D$125207,826D
Class A Common Stock07/09/2026S(1)1,117D$125206,709D
Class A Common Stock07/09/2026S(1)1,355D$125205,354D
Class A Common Stock07/09/2026S(1)1,354D$125204,000D
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)$8.6507/09/2026M174 (2)01/18/2033Class A Common Stock174$8.6535,826D
Stock Option (right to buy)$30.7807/09/2026M1,117 (2)09/30/2035Class A Common Stock1,117$30.7863,883D
Stock Option (right to buy)$30.7807/09/2026M1,355 (2)09/30/2035Class A Common Stock1,355$30.7862,528D
Stock Option (right to buy)$30.7807/09/2026M1,354 (2)09/30/2035Class A Common Stock1,354$30.7861,174D
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 options are fully vested and exercisable. The terms of the underlying option grant are as previously reported on the Reporting Person's Form 3 filed on November 5, 2025.
Remarks:
/s/ Thomas P. Lynch, Attorney-in-Fact07/13/2026
** 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)