X0609 4 2026-06-09 1 0002070849 BillionToOne, Inc. BLLN 0001696926 NeoTribe Ventures I, L.P. false 1300 EL CAMINO REAL, SUITE 100 MENLO PARK CA 94025 0 0 1 0 0001847148 Neotribe Ignite Fund I, L.P. false 1300 EL CAMINO REAL, SUITE 100 MENLO PARK CA 94025 0 0 1 0 0001914071 Neotribe SPV I BTO, LLC false 1300 EL CAMINO REAL, SUITE 100 MENLO PARK CA 94025 0 0 1 0 0001696927 NeoTribe Associates I, L.P. false 1300 EL CAMINO REAL, SUITE 100 MENLO PARK CA 94025 0 0 1 0 0001847146 Neotribe Ignite Partners I, LLC false 1300 EL CAMINO REAL, SUITE 100 MENLO PARK CA 94025 0 0 1 0 0001914068 Neotribe Partners SPV I BTO, LLC false 1300 EL CAMINO REAL, SUITE 100 MENLO PARK CA 94025 0 0 1 0 0001696925 NeoTribe Partners I, LLC false 1300 EL CAMINO REAL, SUITE 100 MENLO PARK CA 94025 0 0 1 0 0 Class A Common Stock 2026-06-09 4 J 0 129780 0 D 1038239 I See Footnote Class A Common Stock 2026-06-09 4 J 0 7980 0 A 7980 I See Footnote Class A Common Stock 2026-06-09 4 J 0 7980 0 D 0 I See Footnote Class A Common Stock 2026-06-09 4 J 0 24222 0 D 193772 I See Footnote Class A Common Stock 2026-06-09 4 J 0 1425 0 A 1425 I See Footnote Class A Common Stock 2026-06-09 4 J 0 1425 0 D 0 I See Footnote Class A Common Stock 2026-06-09 4 J 0 271028 0 D 2168230 D Class A Common Stock 2026-06-09 4 J 0 5423 0 A 5423 I See Footnote Class A Common Stock 2026-06-09 4 J 0 5423 0 D 0 I See Footnote Class A Common Stock 2026-06-09 4 J 0 10921 0 D 87362 D Represents a pro-rata, in-kind distribution by Neotribe Ignite Fund I, L.P. ("NTIF I") to its partners, for no additional consideration. The reported security is directly held by NTIF I. Neotribe Ignite Partners I, LLC ("NTIP I") is the general partner of NTIF I. Krishna Kittu Kolluri ("Kolluri") is the managing member of NTIP I and therefore may be deemed to have voting and dispositive power over the shares held by NTIF I. Kolluri disclaims beneficial ownership of the shares held by NTIF I except to the extent of his pecuniary interest therein. The shares were obtained pursuant to a pro-rata, in-kind distribution from NTIF I, for no additional consideration. The reported security is directly held by NTIP I. Kolluri is the managing member of NTIP I and therefore may be deemed to have voting and dispositive power over the shares held by NTIP I. Kolluri disclaims beneficial ownership of the shares held by NTIP I except to the extent of his pecuniary interest therein. Represents a pro-rata, in-kind distribution by NTIP I to its members and assignees, for no additional consideration. Represents a pro-rata, in-kind distribution by Neotribe SPV I BTO, LLC ("NT SPV I") to its members, for no additional consideration. The reported security is directly held by NT SPV I. Neotribe Partners SPV I BTO, LLC ("NTP SPV I") is the managing member of NT SPV I. Kolluri is the managing member of NTP SPV I and therefore may be deemed to have voting and dispositive power over the shares held by NT SPV I. Kolluri disclaims beneficial ownership of the shares held by NT SPV I except to the extent of his pecuniary interest therein. The shares were obtained pursuant to a pro-rata, in-kind distribution from NT SPV I, for no additional consideration. The reported security is directly held by NTP SPV I. Kolluri is the managing member of NTP SPV I and therefore may be deemed to have voting and dispositive power over the shares held by NTP SPV I. Kolluri disclaims beneficial ownership of the shares held by NTP SPV I except to the extent of his pecuniary interest therein. Represents a pro-rata, in-kind distribution by NTP SPV I to its members and assignees, for no additional consideration. Represents a pro-rata, in-kind distribution by NeoTribe Ventures I, L.P. ("NTV I") to its partners, for no additional consideration. The reported security is directly held by NTV I, for itself. NeoTribe Partners I, LLC ("NTP I") is the general partner of NTV I. Kolluri is the managing member of NTP I and therefore may be deemed to hold voting and dispositive power over the shares held by NTV I. Kolluri disclaims beneficial ownership of the shares held by NTV I except to the extent of his pecuniary interest therein. The shares were obtained pursuant to a pro-rata, in-kind distribution from NTV I, for no additional consideration. The reported security is directly held by NTP I. Kolluri is the managing member of NTP I and therefore may be deemed to have voting and dispositive power over the shares held by NTP I. Kolluri disclaims beneficial ownership of the shares held by NTP I except to the extent of his pecuniary interest therein. Represents a pro-rata, in-kind distribution by NTP I to its members and assignees, for no additional consideration. Represents a pro-rata, in-kind distribution by NeoTribe Associates I, L.P. ("NTA I") to its partners, for no additional consideration. The reported security is directly held by NTV I, as nominee for NTA I. NTP I is the general partner of NTA I. Kolluri is the managing member of NTP I and therefore may be deemed to hold voting and dispositive power over the shares held by NTA I. Kolluri disclaims beneficial ownership of the shares held by NTA I except to the extent of his pecuniary interest therein. This Form 4 is one of two Form 4s filed in respect of the distribution of these shares held of record by NTIF I, NT SPV I, NTV I and NTA I. The Reporting Person for the other Form 4 is Krishna Kittu Kolluri. NeoTribe Ventures I, L.P., by: NeoTribe Partners I, LLC, its general partner, by: /s/ Krishna Kolluri, Managing Member 2026-06-11 NeoTribe Associates I, L.P., by: NeoTribe Partners I, LLC, its general partner, by: /s/ Krishna Kolluri, Managing Member 2026-06-11 Neotribe Ignite Fund I, L.P., by: Neotribe Ignite Partners I, LLC, its general partner, by: /s/ Krishna Kolluri, Managing Member 2026-06-11 Neotribe SPV I BTO, LLC, by: Neotribe Partners SPV I BTO, LLC, its managing member, by: /s/ Krishna Kolluri, Managing Member 2026-06-11 NeoTribe Partners I, LLC, by: /s/ Krishna Kolluri, Managing Member 2026-06-11 Neotribe Ignite Partners I, LLC, by: /s/ Krishna Kolluri, Managing Member 2026-06-11 Neotribe Partners SPV I BTO, LLC, by: /s/ Krishna Kolluri, Managing Member 2026-06-11