Latest Period
Q1 2026
Security Snapshot
MBX Biosciences, Inc. - COMMON STOCK (MBX) Institutional Ownership
CUSIP: 55287L101
13F Institutional Holders and Ownership History from Q3 2024 to Q1 2026
Institutions Reporting
155
Shares (Excl. Options)
52,523,690
Price
$29.85
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- Security type / class
- Equity / COMMON STOCK
- Symbol
- MBX on Nasdaq
- All holders as of 31 Mar 2026
- Q1 2026
- Total 13F shares
- 52,523,690
- Total 13F value
- $1,567,289,456
- Portfolio coverage rank
- 0%
- Share change
- +3,931,276
- Value change
- +$114,687,441
- Number of holders
- 155
- Shares outstanding
- 47,365,871
- SEC-reported price per share
- $36.98
- Insider filing price
- $36.98
Latest holder snapshot
5 signals
Issuer context
Names, identifiers, and filing context for this profile.
3 identity fields
13F Shares, Excluding Options vs Price
13F Value, Excluding Options
Total Investors
Key facts
- MBX - MBX Biosciences, Inc. - COMMON STOCK is tracked under CUSIP 55287L101.
- 155 institutions reported positions in Q1 2026.
- 10 significant owners is listed from Schedule 13D/13G reporting.
Change
- Holder count moved from 138 to 155 between Q4 2025 and Q1 2026.
- SEC-reported value moved from $1,527,258,385 to $1,567,289,456.
Research use
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Evidence
Source: SEC Form 13F
Open SEC evidence
Latest holder context comes from 155 institutions filings for Q1 2026.
Security key
55287L101
Latest holder period
Q1 2026
13F holders
155
13D/G owners
10
CIK / CUSIP context first
Open Q1 2026 holders
MBX full holder history
MBX Biosciences, Inc. SEC filings
MBX Biosciences, Inc. company facts
MBX Biosciences, Inc. insider transactions
Broader feeds
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP 55287L101:
13D/G owners
Significant owners
Large-stake holder rows connected to Schedule 13D/G evidence.
Rows
10
Security
MBX
| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| Frazier Life Sciences Public Fund, L.P. | 12% | -14% | $72,562,680 | +$9,264,602 | 5,224,095 | +15% | Patrick J. Heron | 26 Sep 2025 |
| ORBIMED ADVISORS LLC | 7.7% | -14% | $118,413,222 | -$11,880,750 | 3,637,887 | -9.1% | ORBIMED ADVISORS LLC | 05 Feb 2026 |
| New Enterprise Associates 17, L.P. | 8.1% | $63,340,795 | 3,619,474 | Edward T. Mathers | 06 Nov 2025 | |||
| WELLINGTON MANAGEMENT GROUP LLP | 7.5% | -30% | $109,041,231 | -$47,958,356 | 3,349,961 | -31% | Wellington Management Group LLP | 31 Dec 2025 |
| FMR LLC | 6.2% | $87,660,017 | 2,936,684 | FMR LLC | 31 Mar 2026 | |||
| BlackRock, Inc. | 4.8% | -6% | $68,281,785 | +$487,630 | 2,287,497 | +0.72% | BlackRock, Inc. | 31 Mar 2026 |
| Deep Track Capital, LP | 6.6% | $28,604,897 | 2,188,592 | Deep Track Capital, LP | 30 Jun 2025 | |||
| Norwest Venture Partners XVI, LP | 4.8% | $29,738,337 | 2,140,989 | Tiba Aynechi | 26 Sep 2025 | |||
| Wellington Biomedical Innovation Master Investors (Cayman) II L.P. | 4.5% | $35,304,395 | 2,017,394 | Wellington Biomedical Innovation Master Investors (Cayman) II, L.P. | 30 Sep 2025 | |||
| Hawryluk P. Kent | 4.3% | $34,925,782 | 1,995,759 | P. Kent Hawryluk | 30 Sep 2025 |
As of 31 Mar 2026, 155 institutional investors reported holding 52,523,690 shares of MBX Biosciences, Inc. - COMMON STOCK (MBX). This represents 111% of the company’s total 47,365,871 outstanding shares.
13F concentration
Top 25 institutional shareholders
Largest 13F positions for this security by reported shares and value.
Top holder share
95%
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| Frazier Life Sciences Management, L.P. | 14% | 6,652,013 | 0% | 5.1% | $198,562,588 |
| ORBIMED ADVISORS LLC | 7.7% | 3,637,887 | -7.6% | 2.5% | $108,590,927 |
| NEA Management Company, LLC | 7.6% | 3,614,486 | 0% | 6.1% | $107,892,407 |
| WELLINGTON MANAGEMENT GROUP LLP | 6.7% | 3,191,824 | -4.7% | 0.02% | $95,275,947 |
| BlackRock, Inc. | 6.2% | 2,941,406 | +0.74% | 0% | $87,800,969 |
| FMR LLC | 6.2% | 2,936,684 | +18550% | 0% | $87,660,017 |
| Deep Track Capital, LP | 5.8% | 2,757,569 | -15% | 1.7% | $82,313,435 |
| NVP ASSOCIATES, LLC | 4.5% | 2,136,335 | 0% | 36% | $63,769,600 |
| Polar Capital Holdings Plc | 3.4% | 1,622,186 | 0.21% | $48,422,252 | |
| BRAIDWELL LP | 3.2% | 1,492,467 | +47% | 1.5% | $44,550,140 |
| VANGUARD CAPITAL MANAGEMENT LLC | 3.1% | 1,477,592 | 0% | 0% | $44,106,121 |
| Aaron Wealth Advisors LLC | 2.5% | 1,168,176 | +1569% | 2% | $34,870,054 |
| Cormorant Asset Management, LP | 2.4% | 1,120,000 | 0% | 1.7% | $33,432,000 |
| PRICE T ROWE ASSOCIATES INC /MD/ | 2.2% | 1,029,007 | +22% | 0% | $30,717,000 |
| Driehaus Capital Management LLC | 2.1% | 1,018,212 | -28% | 0.22% | $30,393,628 |
| Kynam Capital Management, LP | 2% | 934,799 | 0% | 1.8% | $27,903,750 |
| CITADEL ADVISORS LLC | 2% | 932,833 | +15% | 0.02% | $27,845,065 |
| Woodline Partners LP | 1.9% | 900,063 | -10% | 0.1% | $26,866,881 |
| EVENTIDE ASSET MANAGEMENT, LLC | 1.9% | 890,000 | 0% | 0.44% | $26,566,500 |
| Caligan Partners LP | 1.8% | 848,590 | 1.8% | $25,330,412 | |
| Parkman Healthcare Partners LLC | 1.7% | 800,037 | -9.7% | 2.5% | $23,881,104 |
| STATE STREET CORP | 1.7% | 787,208 | +17% | 0% | $23,498,159 |
| EcoR1 Capital, LLC | 1.6% | 777,000 | -63% | 0.99% | $23,193,450 |
| GEODE CAPITAL MANAGEMENT, LLC | 1.4% | 670,385 | +3.2% | 0% | $20,015,778 |
| TCG Crossover Management, LLC | 1.4% | 650,000 | 0% | 0.56% | $19,402,500 |
Quarter history
Institutional holders across reporting periods
Holder count, reported shares/value, and median price by quarter.
Periods
7
Latest
Q1 2026
Rows shown
1-7 of 7
| Period | 13F Shares, Excl. Options | Value, Excl. Options | Value Change | Price (Median) | Investors |
|---|---|---|---|---|---|
| 2026 Q1 | 52,523,690 | $1,567,289,456 | +$114,687,441 | $29.85 | 155 |
| 2025 Q4 | 48,428,720 | $1,527,258,385 | +$34,720,034 | $31.54 | 138 |
| 2025 Q3 | 47,790,065 | $836,364,494 | +$203,956,820 | $17.50 | 117 |
| 2025 Q2 | 36,839,365 | $420,338,016 | +$15,667,999 | $11.41 | 87 |
| 2025 Q1 | 35,666,401 | $263,219,997 | +$14,436,597 | $7.38 | 79 |
| 2024 Q4 | 32,941,714 | $606,485,118 | +$45,787,522 | $18.43 | 63 |
| 2024 Q3 | 30,305,441 | $784,071,713 | +$784,024,689 | $25.98 | 45 |