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Arkin Bio Venture Partners Ltd. is the general partner of Arkin Bio. The Reporting Person, a member of the board of directors of the Issuer, is the Biotech Investment Manager of the Pharma Division of Arkin Holdings, and, as a result, may be deemed to share voting and investment power with respect to the shares held by Arkin Bio. The Reporting Person disclaims beneficial ownership of the shares held by Arkin Bio, except to the extent of his pecuniary interest therein."}],"balance_after":2013102,"source":{"system":"sec-edgar","filing":"0001209191-20-024228","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1808244/000120919120024228/doc4.xml","form_type":"4"}},{"id":3178070,"issuer":{"id":6242,"kind":"organization","name":"Keros Therapeutics, Inc."},"owners":[{"id":78513,"kind":"person","name":"Lazarus Alon","position":1,"cik":"0001808244","reported_name":"Lazarus Alon","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2020-04-13T17:15:10.000Z","date":"2020-04-13","kind":"exercise","acquired":true,"shares":167537,"ownership":{"direct":false,"nature":"See footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Preferred Stock, Series B-1 Preferred Stock and Series C Preferred Stock converted into shares of Common Stock upon the closing of the Issuer's initial public offering, on a one-for-one basis, and had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The securities are held by Arkin Bio Ventures Limited Partnership (\"Arkin Bio\"). Arkin Bio Venture Partners Ltd. is the general partner of Arkin Bio. The Reporting Person, a member of the board of directors of the Issuer, is the Biotech Investment Manager of the Pharma Division of Arkin Holdings, and, as a result, may be deemed to share voting and investment power with respect to the shares held by Arkin Bio. The Reporting Person disclaims beneficial ownership of the shares held by Arkin Bio, except to the extent of his pecuniary interest therein."}],"balance_after":1893102,"source":{"system":"sec-edgar","filing":"0001209191-20-024228","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1808244/000120919120024228/doc4.xml","form_type":"4"}},{"id":3178069,"issuer":{"id":6242,"kind":"organization","name":"Keros Therapeutics, Inc."},"owners":[{"id":78513,"kind":"person","name":"Lazarus Alon","position":1,"cik":"0001808244","reported_name":"Lazarus Alon","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2020-04-13T17:15:10.000Z","date":"2020-04-13","kind":"exercise","acquired":true,"shares":343270,"ownership":{"direct":false,"nature":"See footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Preferred Stock, Series B-1 Preferred Stock and Series C Preferred Stock converted into shares of Common Stock upon the closing of the Issuer's initial public offering, on a one-for-one basis, and had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The securities are held by Arkin Bio Ventures Limited Partnership (\"Arkin Bio\"). Arkin Bio Venture Partners Ltd. is the general partner of Arkin Bio. The Reporting Person, a member of the board of directors of the Issuer, is the Biotech Investment Manager of the Pharma Division of Arkin Holdings, and, as a result, may be deemed to share voting and investment power with respect to the shares held by Arkin Bio. The Reporting Person disclaims beneficial ownership of the shares held by Arkin Bio, except to the extent of his pecuniary interest therein."}],"balance_after":1725565,"source":{"system":"sec-edgar","filing":"0001209191-20-024228","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1808244/000120919120024228/doc4.xml","form_type":"4"}},{"id":3178068,"issuer":{"id":6242,"kind":"organization","name":"Keros Therapeutics, Inc."},"owners":[{"id":78513,"kind":"person","name":"Lazarus Alon","position":1,"cik":"0001808244","reported_name":"Lazarus Alon","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2020-04-13T17:15:10.000Z","date":"2020-04-13","kind":"exercise","acquired":true,"shares":1382295,"ownership":{"direct":false,"nature":"See footnote"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Preferred Stock, Series B-1 Preferred Stock and Series C Preferred Stock converted into shares of Common Stock upon the closing of the Issuer's initial public offering, on a one-for-one basis, and had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The securities are held by Arkin Bio Ventures Limited Partnership (\"Arkin Bio\"). Arkin Bio Venture Partners Ltd. is the general partner of Arkin Bio. The Reporting Person, a member of the board of directors of the Issuer, is the Biotech Investment Manager of the Pharma Division of Arkin Holdings, and, as a result, may be deemed to share voting and investment power with respect to the shares held by Arkin Bio. The Reporting Person disclaims beneficial ownership of the shares held by Arkin Bio, except to the extent of his pecuniary interest therein."}],"balance_after":1382295,"source":{"system":"sec-edgar","filing":"0001209191-20-024228","document":"doc4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1808244/000120919120024228/doc4.xml","form_type":"4"}}]}