Form 4 Filing for BillionToOne, Inc.

John Roderick ten Bosch, Senior Vice President of Laboratory Operations at BillionToOne, Inc., reported the sale of 1416 shares of Class A Common Stock on June 15, 2026. The shares were sold at a price of $101.47 per share, resulting in a total transaction value of $143,711.52. This transaction was executed as part of a Rule 10b5-1 trading plan adopted on March 6, 2026. Following this transaction, Mr. ten Bosch directly owns 34,968 shares of Class A Common Stock.