{"transactions":[{"id":4620984,"issuer":{"id":5743,"kind":"organization","name":"Upstream Bio, Inc.","symbol":"UPB"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO and COO"}}],"security":"Common Stock","published_at":"2026-09-17T20:05:26.000Z","date":"2026-09-16","kind":"sale","planned":false,"acquired":false,"shares":853,"price":5.49,"value":4682.97,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The Issuer has adopted a \"sell-to-cover\" policy to satisfy the tax withholding obligations of the Reporting Person. The sales reported on this Form 4 represent the number of shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units. Such sales were automatic and not at the discretion of the Reporting Person."}],"balance_after":27942,"source":{"system":"sec-edgar","filing":"0001193125-26-394322","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/2022626/000119312526394322/ownership.xml","form_type":"4"}},{"id":734514,"issuer":{"id":5743,"kind":"organization","name":"Upstream Bio, Inc.","symbol":"UPB"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO and COO"}}],"security":"Common Stock","published_at":"2026-06-17T20:05:13.000Z","date":"2026-06-16","kind":"sale","planned":false,"acquired":false,"shares":853,"price":6.1,"value":5203.3,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The Issuer has adopted a \"sell-to-cover\" policy to satisfy the tax withholding obligations of the Reporting Person. The sales reported on this Form 4 represent the number of shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units. Such sales were automatic and not at the discretion of the Reporting Person."}],"balance_after":28795,"source":{"system":"sec-edgar","filing":"0001193125-26-274126","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/2022626/000119312526274126/ownership.xml","form_type":"4"}},{"id":838588,"issuer":{"id":5743,"kind":"organization","name":"Upstream Bio, Inc.","symbol":"UPB"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO and COO"}}],"security":"Common Stock","published_at":"2026-03-17T21:03:33.000Z","date":"2026-03-16","kind":"sale","planned":false,"acquired":false,"shares":852,"price":9.29,"value":7915.08,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The Issuer has adopted a \"sell-to-cover\" policy to satisfy the tax withholding obligations of the Reporting Person. The sales reported on this Form 4 represent the number of shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units. Such sales were automatic and not at the discretion of the Reporting Person."}],"balance_after":29648,"source":{"system":"sec-edgar","filing":"0001193125-26-111138","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/2022626/000119312526111138/ownership.xml","form_type":"4"}},{"id":947294,"issuer":{"id":5743,"kind":"organization","name":"Upstream Bio, Inc.","symbol":"UPB"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO and COO"}}],"security":"Stock Option (Right to Buy)","published_at":"2026-01-06T22:15:10.000Z","date":"2026-01-02","kind":"grant","planned":false,"acquired":true,"shares":91500,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F2","text":"The shares underlying this option shall vest in forty-eight equal monthly installments following January 1, 2026, subject to the Reporting Person's continued service on each such vesting date."}],"balance_after":91500,"derivative":{"exercise_price":27.07,"expiration_date":"2036-01-01","underlying":"Common Stock","underlying_shares":91500},"source":{"system":"sec-edgar","filing":"0001193125-26-004758","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/2022626/000119312526004758/ownership.xml","form_type":"4"}},{"id":947293,"issuer":{"id":5743,"kind":"organization","name":"Upstream Bio, Inc.","symbol":"UPB"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO and COO"}}],"security":"Common Stock","published_at":"2026-01-06T22:15:10.000Z","date":"2026-01-02","kind":"grant","planned":false,"acquired":true,"shares":30500,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"Represents restricted stock units (\"RSUs\") granted pursuant to the Issuer's 2024 Stock Option and Incentive Plan. Each RSU represents the contingent right to receive one share of the Issuer's Common Stock upon vesting. The RSUs shall vest in sixteen equal quarterly installments following January 1, 2026, subject to the Reporting Person's continued service on each such vesting date."}],"balance_after":30500,"source":{"system":"sec-edgar","filing":"0001193125-26-004758","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/2022626/000119312526004758/ownership.xml","form_type":"4"}},{"id":1278971,"issuer":{"id":5743,"kind":"organization","name":"Upstream Bio, Inc.","symbol":"UPB"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO and COO"}}],"security":"Stock Option (Right to Buy)","published_at":"2025-02-07T22:31:01.000Z","date":"2025-02-06","kind":"grant","planned":false,"acquired":true,"shares":195000,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"The shares underlying this option shall vest in forty-eight equal monthly installments following February 6, 2025, subject to the Reporting Person's continued service on each such vesting date."}],"balance_after":195000,"derivative":{"exercise_price":8.53,"expiration_date":"2035-02-05","underlying":"Common Stock","underlying_shares":195000},"source":{"system":"sec-edgar","filing":"0000950170-25-016469","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/2022626/000095017025016469/ownership.xml","form_type":"4"}},{"id":1999915,"issuer":{"id":4024,"kind":"organization","name":"Enliven Therapeutics, Inc.","symbol":"ELVN"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO & COO"}}],"security":"Common Stock","published_at":"2023-02-23T01:26:54.000Z","date":"2023-02-22","kind":"sale","acquired":false,"shares":9856,"price":4.67,"value":46027.52,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported on this Form 4 represent shares sold by the Reporting Person to cover tax withholding obligations in connection with the vesting and settlement of restricted stock units."}],"balance_after":27610,"source":{"system":"sec-edgar","filing":"0001209191-23-012016","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1672619/000120919123012016/doc4.xml","form_type":"4"}},{"id":2038556,"issuer":{"id":4024,"kind":"organization","name":"Enliven Therapeutics, Inc.","symbol":"ELVN"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO & COO"}}],"security":"Common Stock","published_at":"2023-02-01T23:26:36.000Z","date":"2023-01-30","kind":"sale","acquired":false,"shares":3596,"price":3.92,"value":14096.32,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported on this Form 4 represent shares sold by the Reporting Person to cover tax withholding obligations in connection with the vesting and settlement of restricted stock units."}],"balance_after":37466,"source":{"system":"sec-edgar","filing":"0001209191-23-005996","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1672619/000120919123005996/doc4.xml","form_type":"4"}},{"id":2419288,"issuer":{"id":4024,"kind":"organization","name":"Enliven Therapeutics, Inc.","symbol":"ELVN"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO & COO"}}],"security":"Stock Option (right to buy)","published_at":"2022-02-01T21:38:40.000Z","date":"2022-01-28","kind":"grant","acquired":true,"shares":39350,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F2","text":"The shares underlying the option vest over four years, with 25% of the shares vesting on the first anniversary of the grant date and the remaining shares vesting in equal quarterly installments thereafter."}],"balance_after":39350,"derivative":{"exercise_price":1.38,"expiration_date":"2032-01-27","underlying":"Common Stock","underlying_shares":39350},"source":{"system":"sec-edgar","filing":"0001209191-22-005926","document":"doc4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1672619/000120919122005926/doc4.xml","form_type":"4"}},{"id":2419287,"issuer":{"id":4024,"kind":"organization","name":"Enliven Therapeutics, Inc.","symbol":"ELVN"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO & COO"}}],"security":"Common Stock","published_at":"2022-02-01T21:38:40.000Z","date":"2022-01-28","kind":"grant","acquired":true,"shares":39350,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The shares underlying the restricted stock unit vest over four years, with 25% of the shares vesting in equal annual installments until the fourth anniversary of the grant date."}],"balance_after":42312,"source":{"system":"sec-edgar","filing":"0001209191-22-005926","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1672619/000120919122005926/doc4.xml","form_type":"4"}},{"id":2892153,"issuer":{"id":4024,"kind":"organization","name":"Enliven Therapeutics, Inc.","symbol":"ELVN"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO & COO"}}],"security":"Stock Option (right to buy)","published_at":"2021-01-28T21:14:55.000Z","date":"2021-01-26","kind":"grant","acquired":true,"shares":60800,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"The shares underlying the option vest over four years, with 25% of the shares vesting on the first anniversary of the grant date and the remaining shares vesting in equal quarterly installments thereafter."}],"balance_after":60800,"derivative":{"exercise_price":13.83,"expiration_date":"2031-01-25","underlying":"Common Stock","underlying_shares":60800},"source":{"system":"sec-edgar","filing":"0001209191-21-005874","document":"doc4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1672619/000120919121005874/doc4.xml","form_type":"4"}},{"id":2944515,"issuer":{"id":4024,"kind":"organization","name":"Enliven Therapeutics, Inc.","symbol":"ELVN"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO & COO"}}],"security":"Stock Option (Right to Buy)","published_at":"2020-12-15T21:26:20.000Z","date":"2020-12-11","kind":"exercise","acquired":false,"shares":1250,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F2","text":"The option was granted on May 16, 2019. The shares underlying the option vest over four years, with 25% of the shares vesting on April 8, 2020 and the remaining shares vesting in equal quarterly installments thereafter."}],"balance_after":223059,"derivative":{"exercise_price":4.92,"expiration_date":"2029-05-15","underlying":"Common Stock","underlying_shares":1250},"source":{"system":"sec-edgar","filing":"0001209191-20-063476","document":"doc4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1672619/000120919120063476/doc4.xml","form_type":"4"}},{"id":2944514,"issuer":{"id":4024,"kind":"organization","name":"Enliven Therapeutics, Inc.","symbol":"ELVN"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO & COO"}}],"security":"Common Stock","published_at":"2020-12-15T21:26:20.000Z","date":"2020-12-11","kind":"sale","acquired":false,"shares":1250,"price":25,"value":31250.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"Transaction made pursuant to Mr. Gray's trading plan under Rule 10b5-1."}],"balance_after":0,"source":{"system":"sec-edgar","filing":"0001209191-20-063476","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1672619/000120919120063476/doc4.xml","form_type":"4"}},{"id":2944513,"issuer":{"id":4024,"kind":"organization","name":"Enliven Therapeutics, Inc.","symbol":"ELVN"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"CFO & COO"}}],"security":"Common Stock","published_at":"2020-12-15T21:26:20.000Z","date":"2020-12-11","kind":"exercise","acquired":true,"shares":1250,"price":4.92,"value":6150.0,"ownership":{"direct":true},"balance_after":1250,"source":{"system":"sec-edgar","filing":"0001209191-20-063476","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1672619/000120919120063476/doc4.xml","form_type":"4"}},{"id":3750472,"issuer":{"id":5638,"kind":"organization","name":"X4 Pharmaceuticals, Inc","symbol":"XFOR"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President, CEO and CFO"}}],"security":"Common Stock","published_at":"2018-11-29T02:50:26.000Z","date":"2018-11-27","kind":"grant","acquired":true,"shares":250000,"price":0,"value":0.0,"ownership":{"direct":true},"balance_after":250000,"source":{"system":"sec-edgar","filing":"0000899243-18-029784","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1271411/000089924318029784/doc4.xml","form_type":"4"}},{"id":4003022,"issuer":{"id":5638,"kind":"organization","name":"X4 Pharmaceuticals, Inc","symbol":"XFOR"},"owners":[{"id":37339,"kind":"person","name":"GRAY MICHAEL","position":1,"cik":"0001271411","reported_name":"GRAY MICHAEL","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"COO and CFO"}}],"security":"Stock option (right to buy)","published_at":"2018-03-09T21:39:07.000Z","date":"2018-03-07","kind":"grant","acquired":true,"shares":110000,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"This option becomes exercisable as to 25% of the shares underlying the award on the first anniversary of the date of grant, with the remainder vesting in equal monthly installments until the fourth anniversary of the date of grant."}],"balance_after":110000,"derivative":{"exercise_price":17.34,"expiration_date":"2028-03-06","underlying":"Common Stock","underlying_shares":110000},"source":{"system":"sec-edgar","filing":"0001209191-18-018523","document":"doc4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1271411/000120919118018523/doc4.xml","form_type":"4"}}]}