BillionToOne Chief Product Officer Riku Sakakibara Executes Stock Option Exercise and Sales

On June 24, 2026, BillionToOne, Inc. Chief Product Officer Riku Sakakibara executed multiple transactions involving company stock. The officer exercised 4,000 stock options at $8.65 per share, acquiring 4,000 shares of Class A Common Stock. Immediately following the exercise, Sakakibara sold 8,000 total shares in two separate transactions at $110 per share each, resulting in net sales proceeds of approximately $880,000. These transactions were executed pursuant to a Rule 10b5-1 trading plan adopted on March 6, 2026, indicating pre-planned trading activity. Following these transactions, Sakakibara's direct holdings decreased to 208,000 shares of Class A Common Stock, with 36,000 stock options remaining. The options exercised were fully vested and exercisable, with original grant terms previously reported on Form 3 filed November 5, 2025.