Form 4 Filing for BillionToOne, Inc. - Officer Stock Transaction

Sakakibara Shan Riku, Chief Product Officer at BillionToOne, Inc., reported two transactions of Class A Common Stock on June 8, 2026. Both transactions were dispositions (code 'D') under a Rule 10b5-1 trading plan. The first transaction involved 4,000 shares at a price of $96.45 per share, resulting in 216,000 shares remaining. The second transaction also involved 4,000 shares, but at a price of $100.00 per share, leaving 212,000 shares. These transactions were executed under a pre-arranged trading plan.