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These shares were sold in multiple transactions at prices ranging from $126.490 to $127.2981 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":11000,"source":{"system":"sec-edgar","filing":"0002087127-26-000004","document":"wk-form4_1784147888.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":7,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000004/wk-form4_1784147888.xml","form_type":"4"}},{"id":709215,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-07-15T20:38:10.000Z","date":"2026-07-13","kind":"sale","planned":true,"acquired":false,"shares":3185,"price":125.8458,"value":400818.873,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $125.4525 to $126.450 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":11821,"source":{"system":"sec-edgar","filing":"0002087127-26-000004","document":"wk-form4_1784147888.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":6,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000004/wk-form4_1784147888.xml","form_type":"4"}},{"id":709214,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-07-15T20:38:10.000Z","date":"2026-07-13","kind":"sale","planned":true,"acquired":false,"shares":2415,"price":124.8996,"value":301632.534,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $124.450 to $125.4325 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":15006,"source":{"system":"sec-edgar","filing":"0002087127-26-000004","document":"wk-form4_1784147888.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000004/wk-form4_1784147888.xml","form_type":"4"}},{"id":709213,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-07-15T20:38:10.000Z","date":"2026-07-13","kind":"sale","planned":true,"acquired":false,"shares":2477,"price":123.8435,"value":306760.3495,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $123.440 to $124.435 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":17421,"source":{"system":"sec-edgar","filing":"0002087127-26-000004","document":"wk-form4_1784147888.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000004/wk-form4_1784147888.xml","form_type":"4"}},{"id":709212,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-07-15T20:38:10.000Z","date":"2026-07-13","kind":"sale","planned":true,"acquired":false,"shares":1102,"price":122.9045,"value":135440.759,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $122.420 to $123.3775 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":19898,"source":{"system":"sec-edgar","filing":"0002087127-26-000004","document":"wk-form4_1784147888.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000004/wk-form4_1784147888.xml","form_type":"4"}},{"id":709211,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common 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These shares were sold in multiple transactions at prices ranging from $104.160 to $104.540 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":1000,"source":{"system":"sec-edgar","filing":"0002087127-26-000002","document":"wk-form4_1781732827.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":13,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000002/wk-form4_1781732827.xml","form_type":"4"}},{"id":734658,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-06-17T21:47:10.000Z","date":"2026-06-15","kind":"sale","planned":true,"acquired":false,"shares":2398,"price":103.6289,"value":248502.1022,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F11","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $103.140 to $104.130 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":1563,"source":{"system":"sec-edgar","filing":"0002087127-26-000002","document":"wk-form4_1781732827.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":12,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000002/wk-form4_1781732827.xml","form_type":"4"}},{"id":734657,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-06-17T21:47:10.000Z","date":"2026-06-15","kind":"sale","planned":true,"acquired":false,"shares":2978,"price":102.5988,"value":305539.2264,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F10","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $101.980 to $102.970 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":3961,"source":{"system":"sec-edgar","filing":"0002087127-26-000002","document":"wk-form4_1781732827.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":11,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000002/wk-form4_1781732827.xml","form_type":"4"}},{"id":734656,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-06-17T21:47:10.000Z","date":"2026-06-15","kind":"sale","planned":true,"acquired":false,"shares":2461,"price":101.3707,"value":249473.2927,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F9","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $100.860 to $101.800 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":6939,"source":{"system":"sec-edgar","filing":"0002087127-26-000002","document":"wk-form4_1781732827.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":10,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000002/wk-form4_1781732827.xml","form_type":"4"}},{"id":734655,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-06-17T21:47:10.000Z","date":"2026-06-15","kind":"sale","planned":true,"acquired":false,"shares":1000,"price":100.053,"value":100053.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F8","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $99.840 to $100.280 per share, inclusive. The holder undertakes to provide, upon written request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote."}],"balance_after":9400,"source":{"system":"sec-edgar","filing":"0002087127-26-000002","document":"wk-form4_1781732827.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":9,"url":"https://www.sec.gov/Archives/edgar/data/2087127/000208712726000002/wk-form4_1781732827.xml","form_type":"4"}},{"id":734654,"issuer":{"id":3992,"kind":"organization","name":"BillionToOne, Inc.","symbol":"BLLN"},"owners":[{"id":19150,"kind":"person","name":"Tsao David","position":1,"cik":"0002087127","reported_name":"Tsao David","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Technology Officer"}}],"security":"Class A Common Stock","published_at":"2026-06-17T21:47:10.000Z","date":"2026-06-15","kind":"sale","planned":true,"acquired":false,"shares":600,"price":98.7417,"value":59245.02,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"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."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $98.160 to $99.080 per share, inclusive. 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