Sakakibara Shan Riku 4

What Happened
Sakakibara Shan Riku, Chief Product Officer of BillionToOne, sold a total of 8,000 shares on June 8, 2026 in two open-market transactions. The sales were 4,000 shares at $96.45 ($385,800) and 4,000 shares at $100.00 ($400,000), for aggregate proceeds of approximately $785,800. These were outright sales (S), which are commonly routine liquidity events rather than affirmative bullish purchases.

Key Details

• Transaction dates and prices: June 8, 2026 — 4,000 shares at $96.45; 4,000 shares at $100.00.
• Total proceeds: ~$785,800.
• Shares owned after transaction: Not disclosed in the provided summary of the Form 4.
• Footnote: Transactions were effected pursuant to a Rule 10b5-1 trading plan adopted March 6, 2026 (pre-scheduled trading plan).
• Filing: Form 4 filed June 10, 2026 (two days after the transactions); appears to be timely.

Context
The trades were executed under a 10b5-1 plan, which generally means the sales were pre-planned and scheduled in advance, reducing the implication that the insider acted on recent, material nonpublic information. As sales, they represent insider liquidity rather than a purchase signal; retail investors should view them as routine insider selling unless additional disclosures or patterns suggest otherwise.