MBX Biosciences, Inc.
Ownership
Ownership Structure
Who owns MBX Biosciences, Inc. (MBX)? This page shows the largest institutions and funds, the ownership structure and the latest insider transactions. 64.3% of the shares are freely tradable; institutional investors hold 111.5%.
Largest Shareholders
Institutions
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| Frazier Life Sciences Management, L.P. | 13.81 | 6,652,013 | +0.0 | 03/31/2026 |
| Wellington Management Company LLP | 10.34 | 4,977,523 | +55.9 | 06/30/2026 |
| Orbimed Advisors LLC | 7.55 | 3,637,887 | -7.6 | 03/31/2026 |
| NEA Management Company, LLC | 7.51 | 3,614,486 | +0.0 | 03/31/2026 |
| BlackRock Inc | 6.11 | 2,941,406 | +0.7 | 03/31/2026 |
| FMR Inc | 6.10 | 2,936,684 | +18,550.3 | 03/31/2026 |
| Paradigm Biocapital Advisors LP | 5.21 | 2,508,015 | +0.0 | 06/30/2026 |
| NVP Associates LLC | 4.44 | 2,136,335 | +0.0 | 06/30/2026 |
| Deep Track Capital, LP | 3.60 | 1,732,569 | -37.2 | 06/30/2026 |
| Polar Capital Holdings PLC | 3.37 | 1,622,186 | +0.0 | 03/31/2026 |
Largest reported positions according to regulatory filings; stake as a percentage of shares outstanding, change versus the previous filing. Source: fundamentals data.
Insider holdings
| Person | Role | Shares | Value | As of | Type |
|---|---|---|---|---|---|
| Hoerter Steven L. | President and CEO | 82,938 | 5,299,738 $ | Aug 3, 2026 | direct |
| Smither John W | Chief Financial Officer | 28,000 | 1,789,200 $ | Aug 3, 2026 | direct |
| Azoulay Salomon | Chief Medical Officer | 14,399 | 920,096 $ | Aug 4, 2026 | direct |
Holdings as of each person's most recent SEC Form 4 filing — excluding options and RSUs, which are not shares yet. Holdings may have changed between two filings.
Insiders
Insider Transactions
| Date | Person | Role | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| Aug 4, 2026 | Azoulay Salomon | Chief Medical Officer | Sell | 370 | 65.77 | 24,335 |
| Aug 3, 2026 | Smither John W | Chief Financial Officer | Other | 28,000 | 0.00 | – |
| Aug 3, 2026 | Hoerter Steven L. | President and CEO | Other | 71,000 | 0.00 | – |
Reportable transactions by officers and major shareholders from SEC Form 4 filings. "Other" includes things like stock grants and option exercises without a buy/sell character. View all insider transactions →
Data as of: September 17, 2026 · Source: fundamental data & SEC filings (annual and quarterly reports, 10-K/10-Q)
Note: pure fact-based analysis, not investment advice and not a solicitation to buy or sell. All figures without guarantee.