Who owns MBX?
Institutional ownership of MBX Biosciences Inc. from Form 13F, Q2 2026
173 institutional managers reported holding MBX Biosciences Inc. (MBX) in Form 13F filings for Q2 2026, with 55,478,890 shares worth $3.1B. The largest reported holder was Frazier Life Sciences Management, L.P. Managers that filed both quarters added a net 2,432,693 shares (+4.6%). 36 opened new positions and 20 sold out.
- Funds holding
- 173
- Value held
- $3.1B
- New / sold out
- 36 / 20
- Net shares, same filers
- +4.6%
Holdings as of June 30, 2026, the end of Q2 2026. Managers have 45 days after a quarter ends to file Form 13F (by August 14, 2026 for Q2 2026), so positions may have changed since.
Largest holders of MBX
| Fund | Value | Share of 13F holdings | Shares | Move |
|---|---|---|---|---|
| Frazier Life Sciences Management, L.P. | $367M | 12.0% | 6,652,013 | Unchanged |
| FMR LLC | $294M | 9.6% | 5,322,885 | Added |
| Wellington Management Group LLP | $275M | 9.0% | 4,977,523 | Added |
| NEA Management Company, LLC | $200M | 6.5% | 3,614,486 | Unchanged |
| Orbimed Advisors LLC | $189M | 6.2% | 3,428,736 | Trimmed |
| BlackRock, Inc. | $183M | 6.0% | 3,323,672 | Added |
| Paradigm Biocapital Advisors LP | $138M | 4.5% | 2,508,015 | New |
| NVP Associates, LLC | $118M | 3.9% | 2,136,335 | Unchanged |
| Deep Track Capital, LP | $95.6M | 3.1% | 1,732,569 | Trimmed |
| Polar Capital Holdings Plc | $88.8M | 2.9% | 1,608,514 | Trimmed |
| Vanguard Capital Management LLC | $81.6M | 2.7% | 1,477,388 | Unchanged |
| Aaron Wealth Advisors LLC | $64.5M | 2.1% | 1,167,799 | Unchanged |
| Driehaus Capital Management LLC | $58.3M | 1.9% | 1,056,579 | Added |
| Kynam Capital Management, LP | $51.6M | 1.7% | 934,799 | Unchanged |
| Woodline Partners LP | $49.7M | 1.6% | 900,092 | Unchanged |
| Eventide Asset Management, LLC | $48.2M | 1.6% | 873,492 | Trimmed |
| State Street Corp | $47.7M | 1.6% | 864,466 | Added |
| Price T Rowe Associates Inc | $45.0M | 1.5% | 814,807 | Trimmed |
| Parkman Healthcare Partners LLC | $44.2M | 1.4% | 800,173 | Unchanged |
| Geode Capital Management, LLC | $42.7M | 1.4% | 773,072 | Added |
| Braidwell LP | $39.2M | 1.3% | 710,880 | Trimmed |
| TCG Crossover Management, LLC | $35.9M | 1.2% | 650,000 | Unchanged |
| Cormorant Asset Management, LP | $30.4M | 1.0% | 550,000 | Trimmed |
| Soleus Capital Management, L.P. | $28.4M | 0.9% | 515,279 | Added |
| Goldman Sachs Group Inc | $25.3M | 0.8% | 459,005 | Added |
Share of 13F holdings is each fund's shares as a share of the 55,478,890 MBX shares all 13F filers reported, not of shares outstanding.
Biggest buyers in Q2 2026
- Paradigm Biocapital Advisors LP New+$138M
- FMR LLC Added+$132M
- Wellington Management Group LLP Added+$98.6M
- BlackRock, Inc. Added+$21.1M
- Marshall Wace, LLP Added+$18.7M
- Soleus Capital Management, L.P. Added+$18.6M
- Bank of America Corp Added+$14.9M
- Franklin Resources Inc New+$13.9M
- Morgan Stanley Added+$12.0M
- Dimensional Fund Advisors LP Added+$10.3M
Biggest sellers in Q2 2026
- Deep Track Capital, LP Trimmed-$56.6M
- Braidwell LP Trimmed-$43.1M
- Caligan Partners LP Trimmed-$35.8M
- Cormorant Asset Management, LP Trimmed-$31.5M
- Stempoint Capital LP Sold out-$29.8M
- Citadel Advisors LLC Sold out-$27.8M
- EcoR1 Capital, LLC Trimmed-$21.4M
- Millennium Management LLC Trimmed-$18.7M
- Price T Rowe Associates Inc Trimmed-$11.8M
- Orbimed Advisors LLC Trimmed-$11.5M
The change in shares since the quarter before, adjusted for stock splits and priced at the Q2 2026 value per share. Funds bought $548M and sold $355M; 62 added and 47 trimmed.
Schedule 13D and 13G filings on MBX
Owners of more than 5% must file within days, so these can be newer than the 13F data.
- 2026-07-29BlackRock, Inc. SCHEDULE 13G filed by BlackRock Inc.Schedule 13G
- 2026-05-06FMR LLC SCHEDULE 13G filed by MBX Biosciences Inc.Schedule 13G
- 2026-01-21BlackRock, Inc. SCHEDULE 13G filed by BlackRock Inc.Schedule 13G
Questions about MBX ownership
- Who owns MBX stock?
- 173 institutional investment managers reported MBX positions in their Form 13F filings for Q2 2026, holding 55,478,890 shares worth $3.1B in total. Frazier Life Sciences Management, L.P. reported the largest position.
- Are funds buying or selling MBX?
- In Q2 2026, 36 managers opened new MBX positions, 62 added, 47 trimmed and 20 sold out. Managers that filed in both quarters added a net 2,432,693 shares.
- How current is this MBX institutional ownership data?
- It covers holdings as of the end of Q2 2026. Managers have 45 days after the quarter ends to file Form 13F (by August 14, 2026 for Q2 2026), so positions may have changed since.
From the SEC's Form 13F data sets for Q2 2026: every 13F holdings report, matched to MBX by CUSIP. Options are left out. MBX news and filings · MBX insider trades · Top funds