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The Reporting Person undertakes, upon request by the staff of the Securities and Exchange Commission, the Issuer or a security holder of the Issuer, to provide full information regarding the number of shares purchased at each separate price."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F4","text":"These securities are held of record by OrbiMed Private Investments VII, LP (\"OPI VII\"). OrbiMed Capital GP VII LLC (\"GP VII\") is the general partner of OPI VII. OrbiMed Advisors LLC (\"OrbiMed Advisors\") is the managing member of GP VII. By virtue of such relationships, OrbiMed Advisors and GP VII may be deemed to have voting power and investment power over the securities held by OPI VII and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of the Reporting Person, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VII."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F6","text":"Each of OrbiMed Advisors, GP VII, Genesis GP, and the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the \"Exchange Act\"), except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose."}],"balance_after":3176390,"source":{"system":"sec-edgar","filing":"0000947871-25-000200","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000094787125000200/ownership.xml","form_type":"4"}},{"id":1261334,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24290,"kind":"person","name":"ORBIMED ADVISORS LLC","position":1,"cik":"0001055951","reported_name":"ORBIMED ADVISORS LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":35791,"kind":"organization","name":"OrbiMed Capital GP VII LLC","position":2,"cik":"0001760648","reported_name":"OrbiMed Capital GP VII LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":24740,"kind":"person","name":"OrbiMed Genesis GP LLC","position":3,"cik":"0001808744","reported_name":"OrbiMed Genesis GP LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-02-19T22:52:03.000Z","date":"2025-02-18","kind":"purchase","planned":false,"acquired":true,"shares":94100,"price":10.84,"value":1020044.0,"ownership":{"direct":false,"nature":"See footnotes"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F3","text":"Represents the weighted average purchase price of the shares of the Issuer's common stock purchased, ranging from a low of $10.25 to a high of $11.46 per share. The Reporting Persons undertake, upon request by the staff of the Securities and Exchange Commission, the Issuer or a security holder of the Issuer, to provide full information regarding the number of shares purchased at each separate price."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F5","text":"These securities are held of record by OrbiMed Genesis Master Fund, L.P. (\"Genesis Master Fund\"). OrbiMed Genesis GP LLC (\"Genesis GP\") is the general partner of Genesis Master Fund. OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, OrbiMed Advisors and Genesis GP may be deemed to have voting power and investment power over the securities held by Genesis Master Fund and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by Genesis Master Fund."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F6","text":"This report on Form 4 is jointly filed by OrbiMed Advisors, GP VII, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the \"Exchange Act\"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Carl L. Gordon, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose."}],"balance_after":747887,"source":{"system":"sec-edgar","filing":"0000947871-25-000199","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1055951/000094787125000199/ownership.xml","form_type":"4"}},{"id":1261333,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24290,"kind":"person","name":"ORBIMED ADVISORS LLC","position":1,"cik":"0001055951","reported_name":"ORBIMED ADVISORS LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":35791,"kind":"organization","name":"OrbiMed Capital GP VII LLC","position":2,"cik":"0001760648","reported_name":"OrbiMed Capital GP VII LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":24740,"kind":"person","name":"OrbiMed Genesis GP LLC","position":3,"cik":"0001808744","reported_name":"OrbiMed Genesis GP LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-02-19T22:52:03.000Z","date":"2025-02-18","kind":"purchase","planned":false,"acquired":true,"shares":49070,"price":10.84,"value":531918.8,"ownership":{"direct":false,"nature":"See footnotes"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F3","text":"Represents the weighted average purchase price of the shares of the Issuer's common stock purchased, ranging from a low of $10.25 to a high of $11.46 per share. The Reporting Persons undertake, upon request by the staff of the Securities and Exchange Commission, the Issuer or a security holder of the Issuer, to provide full information regarding the number of shares purchased at each separate price."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F4","text":"These securities are held of record by OrbiMed Private Investments VII, LP (\"OPI VII\"). OrbiMed Capital GP VII LLC (\"GP VII\") is the general partner of OPI VII. OrbiMed Advisors LLC (\"OrbiMed Advisors\") is the managing member of GP VII. By virtue of such relationships, OrbiMed Advisors and GP VII may be deemed to have voting power and investment power over the securities held by OPI VII and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VII."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F6","text":"This report on Form 4 is jointly filed by OrbiMed Advisors, GP VII, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the \"Exchange Act\"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Carl L. Gordon, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose."}],"balance_after":3255000,"source":{"system":"sec-edgar","filing":"0000947871-25-000199","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1055951/000094787125000199/ownership.xml","form_type":"4"}},{"id":1261332,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24290,"kind":"person","name":"ORBIMED ADVISORS LLC","position":1,"cik":"0001055951","reported_name":"ORBIMED ADVISORS LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":35791,"kind":"organization","name":"OrbiMed Capital GP VII LLC","position":2,"cik":"0001760648","reported_name":"OrbiMed Capital GP VII LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":24740,"kind":"person","name":"OrbiMed Genesis GP LLC","position":3,"cik":"0001808744","reported_name":"OrbiMed Genesis GP LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-02-19T22:52:03.000Z","date":"2025-02-14","kind":"purchase","planned":false,"acquired":true,"shares":29540,"price":9.85,"value":290969.0,"ownership":{"direct":false,"nature":"See footnotes"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F2","text":"Represents the weighted average purchase price of the shares of the Issuer's common stock purchased, ranging from a low of $9.80 to a high of $10.00 per share. The Reporting Persons undertake, upon request by the staff of the Securities and Exchange Commission, the Issuer or a security holder of the Issuer, to provide full information regarding the number of shares purchased at each separate price."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F4","text":"These securities are held of record by OrbiMed Private Investments VII, LP (\"OPI VII\"). OrbiMed Capital GP VII LLC (\"GP VII\") is the general partner of OPI VII. OrbiMed Advisors LLC (\"OrbiMed Advisors\") is the managing member of GP VII. By virtue of such relationships, OrbiMed Advisors and GP VII may be deemed to have voting power and investment power over the securities held by OPI VII and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VII."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F6","text":"This report on Form 4 is jointly filed by OrbiMed Advisors, GP VII, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the \"Exchange Act\"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Carl L. Gordon, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose."}],"balance_after":3205930,"source":{"system":"sec-edgar","filing":"0000947871-25-000199","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1055951/000094787125000199/ownership.xml","form_type":"4"}},{"id":1261331,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24290,"kind":"person","name":"ORBIMED ADVISORS LLC","position":1,"cik":"0001055951","reported_name":"ORBIMED ADVISORS LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":35791,"kind":"organization","name":"OrbiMed Capital GP VII LLC","position":2,"cik":"0001760648","reported_name":"OrbiMed Capital GP VII LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}},{"id":24740,"kind":"person","name":"OrbiMed Genesis GP LLC","position":3,"cik":"0001808744","reported_name":"OrbiMed Genesis GP LLC","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-02-19T22:52:03.000Z","date":"2025-02-14","kind":"purchase","planned":false,"acquired":true,"shares":17962,"price":9.9,"value":177823.8,"ownership":{"direct":false,"nature":"See footnotes"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Represents the weighted average purchase price of the shares of the Issuer's common stock purchased, ranging from a low of $9.58 to a high of $10.20 per share. The Reporting Persons undertake, upon request by the staff of the Securities and Exchange Commission, the Issuer or a security holder of the Issuer, to provide full information regarding the number of shares purchased at each separate price."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F4","text":"These securities are held of record by OrbiMed Private Investments VII, LP (\"OPI VII\"). OrbiMed Capital GP VII LLC (\"GP VII\") is the general partner of OPI VII. OrbiMed Advisors LLC (\"OrbiMed Advisors\") is the managing member of GP VII. By virtue of such relationships, OrbiMed Advisors and GP VII may be deemed to have voting power and investment power over the securities held by OPI VII and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VII."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F6","text":"This report on Form 4 is jointly filed by OrbiMed Advisors, GP VII, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the \"Exchange Act\"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors has designated a representative, Carl L. Gordon, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose."}],"balance_after":3176390,"source":{"system":"sec-edgar","filing":"0000947871-25-000199","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1055951/000094787125000199/ownership.xml","form_type":"4"}},{"id":1282299,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":26302,"kind":"person","name":"Azoulay Salomon","position":1,"cik":"0002030246","reported_name":"Azoulay Salomon","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Medical Officer"}}],"security":"Stock Option (Right to Buy)","published_at":"2025-02-05T21:17:40.000Z","date":"2025-02-03","kind":"grant","planned":false,"acquired":true,"shares":90000,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"25% of the shares underlying this option vest and become exercisable on February 3, 2026, with the remaining 75% vesting in thirty-six (36) equal monthly installments thereafter, subject to the Reporting Person's continued service on such vesting date."}],"balance_after":90000,"derivative":{"exercise_price":10.49,"expiration_date":"2035-02-03","underlying":"Common Stock","underlying_shares":90000},"source":{"system":"sec-edgar","filing":"0000950170-25-014499","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/2030246/000095017025014499/ownership.xml","form_type":"4"}},{"id":1281959,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":67970,"kind":"person","name":"Bartram Richard","position":1,"cik":"0001723729","reported_name":"Bartram Richard","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Financial Officer"}}],"security":"Stock Option (Right to Buy)","published_at":"2025-02-05T21:17:21.000Z","date":"2025-02-03","kind":"grant","planned":false,"acquired":true,"shares":95000,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"25% of the shares underlying this option vest and become exercisable on February 3, 2026, with the remaining 75% vesting in thirty-six (36) equal monthly installments thereafter, subject to the Reporting Person's continued service on such vesting date."}],"balance_after":95000,"derivative":{"exercise_price":10.49,"expiration_date":"2035-02-03","underlying":"Common Stock","underlying_shares":95000},"source":{"system":"sec-edgar","filing":"0000950170-25-014497","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017025014497/ownership.xml","form_type":"4"}},{"id":1282941,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":48947,"kind":"person","name":"Hawryluk P. Kent","position":1,"cik":"0001673991","reported_name":"Hawryluk P. Kent","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Stock Option (Right to Buy)","published_at":"2025-02-05T21:17:07.000Z","date":"2025-02-03","kind":"grant","planned":false,"acquired":true,"shares":243000,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F3","text":"25% of the shares underlying this option vest and become exercisable on February 3, 2026, with the remaining 75% vesting in thirty-six (36) equal monthly installments thereafter, subject to the Reporting Person's continued service on such vesting date."}],"balance_after":243000,"derivative":{"exercise_price":10.49,"expiration_date":"2035-02-03","underlying":"Common Stock","underlying_shares":243000},"source":{"system":"sec-edgar","filing":"0000950170-25-014494","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1673991/000095017025014494/ownership.xml","form_type":"4"}},{"id":1282940,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":48947,"kind":"person","name":"Hawryluk P. Kent","position":1,"cik":"0001673991","reported_name":"Hawryluk P. Kent","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Common Stock","published_at":"2025-02-05T21:17:07.000Z","date":"2025-02-04","kind":"purchase","planned":false,"acquired":true,"shares":50000,"price":10.69,"value":534500.0,"ownership":{"direct":false,"nature":"By Trust"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $10.60 to $10.75, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"Shares held by the P. Kent Hawryluk Revocable Trust dated January 25, 2011, of which the Reporting Person serves as trustee. The Reporting Person disclaims beneficial ownership except to the extent of any pecuniary interest therein, and this report shall not be deemed an admission that such shares are beneficially owned by him for Section 16 or any other purpose."}],"balance_after":448277,"source":{"system":"sec-edgar","filing":"0000950170-25-014494","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1673991/000095017025014494/ownership.xml","form_type":"4"}},{"id":1405219,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24544,"kind":"person","name":"Mathers Edward T","position":1,"cik":"0001328625","reported_name":"Mathers Edward T","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series B Convertible Preferred Stock","published_at":"2024-09-18T00:28:00.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":25142840,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":2091383},"source":{"system":"sec-edgar","filing":"0000950170-24-107558","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107558/ownership.xml","form_type":"4"}},{"id":1405218,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24544,"kind":"person","name":"Mathers Edward T","position":1,"cik":"0001328625","reported_name":"Mathers Edward T","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series A Convertible Preferred Stock","published_at":"2024-09-18T00:28:00.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":12299854,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":1023103},"source":{"system":"sec-edgar","filing":"0000950170-24-107558","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107558/ownership.xml","form_type":"4"}},{"id":1405217,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24544,"kind":"person","name":"Mathers Edward T","position":1,"cik":"0001328625","reported_name":"Mathers Edward T","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:28:00.000Z","date":"2024-09-16","kind":"purchase","planned":false,"acquired":true,"shares":500000,"price":16,"value":8000000.0,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3614486,"source":{"system":"sec-edgar","filing":"0000950170-24-107558","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107558/ownership.xml","form_type":"4"}},{"id":1405216,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24544,"kind":"person","name":"Mathers Edward T","position":1,"cik":"0001328625","reported_name":"Mathers Edward T","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:28:00.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":2091383,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3114486,"source":{"system":"sec-edgar","filing":"0000950170-24-107558","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107558/ownership.xml","form_type":"4"}},{"id":1405215,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":24544,"kind":"person","name":"Mathers Edward T","position":1,"cik":"0001328625","reported_name":"Mathers Edward T","relationship":{"director":true,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:28:00.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":1023103,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":1023103,"source":{"system":"sec-edgar","filing":"0000950170-24-107558","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107558/ownership.xml","form_type":"4"}},{"id":1405224,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61210,"kind":"person","name":"BASKETT FOREST","position":1,"cik":"0001277631","reported_name":"BASKETT FOREST","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series B Convertible Preferred Stock","published_at":"2024-09-18T00:26:31.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":25142840,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":2091383},"source":{"system":"sec-edgar","filing":"0000950170-24-107556","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107556/ownership.xml","form_type":"4"}},{"id":1405223,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61210,"kind":"person","name":"BASKETT FOREST","position":1,"cik":"0001277631","reported_name":"BASKETT FOREST","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series A Convertible Preferred Stock","published_at":"2024-09-18T00:26:31.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":12299854,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":1023103},"source":{"system":"sec-edgar","filing":"0000950170-24-107556","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107556/ownership.xml","form_type":"4"}},{"id":1405222,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61210,"kind":"person","name":"BASKETT FOREST","position":1,"cik":"0001277631","reported_name":"BASKETT FOREST","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:26:31.000Z","date":"2024-09-16","kind":"purchase","planned":false,"acquired":true,"shares":500000,"price":16,"value":8000000.0,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3614486,"source":{"system":"sec-edgar","filing":"0000950170-24-107556","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107556/ownership.xml","form_type":"4"}},{"id":1405221,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61210,"kind":"person","name":"BASKETT FOREST","position":1,"cik":"0001277631","reported_name":"BASKETT FOREST","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:26:31.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":2091383,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3114486,"source":{"system":"sec-edgar","filing":"0000950170-24-107556","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107556/ownership.xml","form_type":"4"}},{"id":1405220,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61210,"kind":"person","name":"BASKETT FOREST","position":1,"cik":"0001277631","reported_name":"BASKETT FOREST","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:26:31.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":1023103,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":1023103,"source":{"system":"sec-edgar","filing":"0000950170-24-107556","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107556/ownership.xml","form_type":"4"}},{"id":1405214,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":31983,"kind":"person","name":"Behbahani Ali","position":1,"cik":"0001613867","reported_name":"Behbahani Ali","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series B Convertible Preferred Stock","published_at":"2024-09-18T00:24:49.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":25142840,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":2091383},"source":{"system":"sec-edgar","filing":"0000950170-24-107554","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107554/ownership.xml","form_type":"4"}},{"id":1405213,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":31983,"kind":"person","name":"Behbahani Ali","position":1,"cik":"0001613867","reported_name":"Behbahani Ali","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series A Convertible Preferred Stock","published_at":"2024-09-18T00:24:49.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":12299854,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":1023103},"source":{"system":"sec-edgar","filing":"0000950170-24-107554","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107554/ownership.xml","form_type":"4"}},{"id":1405212,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":31983,"kind":"person","name":"Behbahani Ali","position":1,"cik":"0001613867","reported_name":"Behbahani Ali","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:24:49.000Z","date":"2024-09-16","kind":"purchase","planned":false,"acquired":true,"shares":500000,"price":16,"value":8000000.0,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3614486,"source":{"system":"sec-edgar","filing":"0000950170-24-107554","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107554/ownership.xml","form_type":"4"}},{"id":1405211,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":31983,"kind":"person","name":"Behbahani Ali","position":1,"cik":"0001613867","reported_name":"Behbahani Ali","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:24:49.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":2091383,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3114486,"source":{"system":"sec-edgar","filing":"0000950170-24-107554","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107554/ownership.xml","form_type":"4"}},{"id":1405210,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":31983,"kind":"person","name":"Behbahani Ali","position":1,"cik":"0001613867","reported_name":"Behbahani Ali","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:24:49.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":1023103,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":1023103,"source":{"system":"sec-edgar","filing":"0000950170-24-107554","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107554/ownership.xml","form_type":"4"}},{"id":1405209,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":38171,"kind":"person","name":"Chang Carmen","position":1,"cik":"0001746342","reported_name":"Chang Carmen","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series B Convertible Preferred Stock","published_at":"2024-09-18T00:23:24.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":25142840,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":2091383},"source":{"system":"sec-edgar","filing":"0000950170-24-107552","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107552/ownership.xml","form_type":"4"}},{"id":1405208,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":38171,"kind":"person","name":"Chang Carmen","position":1,"cik":"0001746342","reported_name":"Chang Carmen","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series A Convertible Preferred Stock","published_at":"2024-09-18T00:23:24.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":12299854,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":1023103},"source":{"system":"sec-edgar","filing":"0000950170-24-107552","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107552/ownership.xml","form_type":"4"}},{"id":1405207,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":38171,"kind":"person","name":"Chang Carmen","position":1,"cik":"0001746342","reported_name":"Chang Carmen","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:23:24.000Z","date":"2024-09-16","kind":"purchase","planned":false,"acquired":true,"shares":500000,"price":16,"value":8000000.0,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3614486,"source":{"system":"sec-edgar","filing":"0000950170-24-107552","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107552/ownership.xml","form_type":"4"}},{"id":1405206,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":38171,"kind":"person","name":"Chang Carmen","position":1,"cik":"0001746342","reported_name":"Chang Carmen","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:23:24.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":2091383,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3114486,"source":{"system":"sec-edgar","filing":"0000950170-24-107552","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107552/ownership.xml","form_type":"4"}},{"id":1405205,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":38171,"kind":"person","name":"Chang Carmen","position":1,"cik":"0001746342","reported_name":"Chang Carmen","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:23:24.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":1023103,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":1023103,"source":{"system":"sec-edgar","filing":"0000950170-24-107552","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107552/ownership.xml","form_type":"4"}},{"id":1405204,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23293,"kind":"person","name":"Florence Anthony A. Jr.","position":1,"cik":"0001559827","reported_name":"Florence Anthony A. 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The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":2091383},"source":{"system":"sec-edgar","filing":"0000950170-24-107549","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107549/ownership.xml","form_type":"4"}},{"id":1405203,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23293,"kind":"person","name":"Florence Anthony A. Jr.","position":1,"cik":"0001559827","reported_name":"Florence Anthony A. 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The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":1023103},"source":{"system":"sec-edgar","filing":"0000950170-24-107549","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107549/ownership.xml","form_type":"4"}},{"id":1405202,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23293,"kind":"person","name":"Florence Anthony A. Jr.","position":1,"cik":"0001559827","reported_name":"Florence Anthony A. 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The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3614486,"source":{"system":"sec-edgar","filing":"0000950170-24-107549","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107549/ownership.xml","form_type":"4"}},{"id":1405201,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23293,"kind":"person","name":"Florence Anthony A. Jr.","position":1,"cik":"0001559827","reported_name":"Florence Anthony A. 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The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3114486,"source":{"system":"sec-edgar","filing":"0000950170-24-107549","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107549/ownership.xml","form_type":"4"}},{"id":1405200,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23293,"kind":"person","name":"Florence Anthony A. Jr.","position":1,"cik":"0001559827","reported_name":"Florence Anthony A. 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The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":1023103,"source":{"system":"sec-edgar","filing":"0000950170-24-107549","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107549/ownership.xml","form_type":"4"}},{"id":1405199,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23295,"kind":"person","name":"Makhzoumi Mohamad","position":1,"cik":"0001630226","reported_name":"Makhzoumi Mohamad","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series B Convertible Preferred Stock","published_at":"2024-09-18T00:20:13.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":25142840,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":2091383},"source":{"system":"sec-edgar","filing":"0000950170-24-107547","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107547/ownership.xml","form_type":"4"}},{"id":1405198,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23295,"kind":"person","name":"Makhzoumi Mohamad","position":1,"cik":"0001630226","reported_name":"Makhzoumi Mohamad","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series A Convertible Preferred Stock","published_at":"2024-09-18T00:20:13.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":12299854,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":1023103},"source":{"system":"sec-edgar","filing":"0000950170-24-107547","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107547/ownership.xml","form_type":"4"}},{"id":1405197,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23295,"kind":"person","name":"Makhzoumi Mohamad","position":1,"cik":"0001630226","reported_name":"Makhzoumi Mohamad","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:20:13.000Z","date":"2024-09-16","kind":"purchase","planned":false,"acquired":true,"shares":500000,"price":16,"value":8000000.0,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3614486,"source":{"system":"sec-edgar","filing":"0000950170-24-107547","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107547/ownership.xml","form_type":"4"}},{"id":1405196,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23295,"kind":"person","name":"Makhzoumi Mohamad","position":1,"cik":"0001630226","reported_name":"Makhzoumi Mohamad","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:20:13.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":2091383,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3114486,"source":{"system":"sec-edgar","filing":"0000950170-24-107547","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107547/ownership.xml","form_type":"4"}},{"id":1405195,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23295,"kind":"person","name":"Makhzoumi Mohamad","position":1,"cik":"0001630226","reported_name":"Makhzoumi Mohamad","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:20:13.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":1023103,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":1023103,"source":{"system":"sec-edgar","filing":"0000950170-24-107547","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107547/ownership.xml","form_type":"4"}},{"id":1405194,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61190,"kind":"person","name":"Walker Paul Edward","position":1,"cik":"0001553150","reported_name":"Walker Paul Edward","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series B Convertible Preferred Stock","published_at":"2024-09-18T00:18:53.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":25142840,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":2091383},"source":{"system":"sec-edgar","filing":"0000950170-24-107544","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107544/ownership.xml","form_type":"4"}},{"id":1405193,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61190,"kind":"person","name":"Walker Paul Edward","position":1,"cik":"0001553150","reported_name":"Walker Paul Edward","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series A Convertible Preferred Stock","published_at":"2024-09-18T00:18:53.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":12299854,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":1023103},"source":{"system":"sec-edgar","filing":"0000950170-24-107544","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107544/ownership.xml","form_type":"4"}},{"id":1405192,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61190,"kind":"person","name":"Walker Paul Edward","position":1,"cik":"0001553150","reported_name":"Walker Paul Edward","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:18:53.000Z","date":"2024-09-16","kind":"purchase","planned":false,"acquired":true,"shares":500000,"price":16,"value":8000000.0,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3614486,"source":{"system":"sec-edgar","filing":"0000950170-24-107544","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107544/ownership.xml","form_type":"4"}},{"id":1405191,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61190,"kind":"person","name":"Walker Paul Edward","position":1,"cik":"0001553150","reported_name":"Walker Paul Edward","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:18:53.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":2091383,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3114486,"source":{"system":"sec-edgar","filing":"0000950170-24-107544","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107544/ownership.xml","form_type":"4"}},{"id":1405190,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":61190,"kind":"person","name":"Walker Paul Edward","position":1,"cik":"0001553150","reported_name":"Walker Paul Edward","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:18:53.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":true,"shares":1023103,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":1023103,"source":{"system":"sec-edgar","filing":"0000950170-24-107544","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107544/ownership.xml","form_type":"4"}},{"id":1405189,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23294,"kind":"person","name":"SANDELL SCOTT D","position":1,"cik":"0001237289","reported_name":"SANDELL SCOTT D","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series B Convertible Preferred Stock","published_at":"2024-09-18T00:14:42.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":25142840,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":2091383},"source":{"system":"sec-edgar","filing":"0000950170-24-107540","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107540/ownership.xml","form_type":"4"}},{"id":1405188,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23294,"kind":"person","name":"SANDELL SCOTT D","position":1,"cik":"0001237289","reported_name":"SANDELL SCOTT D","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Series A Convertible Preferred Stock","published_at":"2024-09-18T00:14:42.000Z","date":"2024-09-16","kind":"exercise","planned":false,"acquired":false,"shares":12299854,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Each share of Series A Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the \"Preferred Stock\") was convertible into Common Stock on a one-for-12.0221 basis at any time at the option of the holder, and automatically converted into the number of shares shown in Column 7 immediately prior to the closing of the Issuer's initial public offering on September 16, 2024. The Preferred Stock had no expiration date."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":0,"derivative":{"underlying":"Common Stock","underlying_shares":1023103},"source":{"system":"sec-edgar","filing":"0000950170-24-107540","document":"ownership.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107540/ownership.xml","form_type":"4"}},{"id":1405187,"issuer":{"id":4247,"kind":"organization","name":"MBX Biosciences, Inc."},"owners":[{"id":23294,"kind":"person","name":"SANDELL SCOTT D","position":1,"cik":"0001237289","reported_name":"SANDELL SCOTT D","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2024-09-18T00:14:42.000Z","date":"2024-09-16","kind":"purchase","planned":false,"acquired":true,"shares":500000,"price":16,"value":8000000.0,"ownership":{"direct":false,"nature":"See Note 2"},"footnotes":[{"field":"ownership.nature","element":"natureOfOwnership","label":"F2","text":"The Reporting Person is a manager of NEA 17 GP, LLC, which is the sole general partner of NEA Partners 17, L.P. (\"NEA Partners 17\"). NEA Partners 17 is the sole general partner of New Enterprise Associates 17, L.P. (\"NEA 17\"), the direct beneficial owner of the securities. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise of such portion of the securities held by NEA 17 in which the Reporting Person has no pecuniary interest."}],"balance_after":3614486,"source":{"system":"sec-edgar","filing":"0000950170-24-107540","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1776111/000095017024107540/ownership.xml","form_type":"4"}}],"next_cursor":"2024-09-18T00:14:42.000000Z,1405187"}