MBX · MBX Biosciences, Inc. · Holdings

$59.02 -1.92 (-3.15%) At close · Sep 11

Russell 2000 member Rebalance outlook locked

Market Cap

$2.84B

48.16M

Institutional ownership from SEC Form 13F filings. Investment managers with more than $100 million in U.S. equities must disclose their positions every quarter, within 45 days of quarter-end, so the holdings shown can lag the market by up to a quarter.

Use institutional holdings through the 13F API or MCP →

Quarter:

Holders: 175

Total Value: $3,094,948,489

Total Shares: 56,067,919

Showing 1–100 of 179 holdings by value · page 1 of 2

Institutional Ownership Trend

8 quarters

Holder Concentration

Across 175 13F filers · Δ vs Mar 31, 2026

Top Holder

11.9%

−0.8 pts

Top 5

42.8%

+4.8 pts

Top 10

63.0%

+4.2 pts

HHI

518

Broadly held+48

Quarterly Activity

vs Mar 31, 2026

New

Increased

Decreased

Sold Out

Unchanged

Holder count: +17

Institutional value: +96.7%

Shares held: +6.4%

Top Buyers

vs Mar 31, 2026

Institution	Added	Now Holds
Mega FMR LLC	+2,386,201	5,322,885
Mega WELLINGTON MANAGEMENT GROUP LLP	+1,785,699	4,977,523
Mega BlackRock, Inc.	+382,266	3,323,672
Large MARSHALL WACE, LLP	+339,182	401,885
Mid Soleus Capital Management, L.P.	+336,382	515,279

Top Sellers

vs Mar 31, 2026

Institution	Sold	Now Holds
Mid Deep Track Capital, LP	−1,025,000	1,732,569
Mega CITADEL ADVISORS LLC	−941,833	26,200
Mid BRAIDWELL LP	−781,587	710,880
Mid Caligan Partners LP	−648,590	200,000
Mid Cormorant Asset Management, LP	−570,000	550,000

Top New Positions

vs Mar 31, 2026

Institution	Acquired	Value (USD)
Mid Paradigm Biocapital Advisors LP	2,508,015	$138,442,428
Large Caption Management, LLC	400,000	$22,080,000
Mega FRANKLIN RESOURCES INC	252,665	$13,947,107
Large PRUDENTIAL FINANCIAL INC	88,045	$4,860,084
Mid MOORE CAPITAL MANAGEMENT, LP	64,893	$3,582,093

Top Sold-Out Positions

vs Mar 31, 2026

Institution	Previously Held	Last Value (USD)
Small STEMPOINT CAPITAL LP	499,469	$14,909,149
Large Squarepoint Ops LLC	97,215	$2,901,867
Mega VICTORY CAPITAL MANAGEMENT INC	71,028	$2,120,185
Mega SCHRODER INVESTMENT MANAGEMENT GROUP	57,322	$1,711,061
Large ExodusPoint Capital Management, LP	28,087	$838,396

Filter: New 39 Increased 64 Reduced 51 Sold out 22 Unchanged 21

Showing 100 of 179

All Common Calls Puts

Compact Export CSV

Holder

Value (USD)

% of 13F

Frazier Life Sciences Management, L.P.

$367,191,117

11.86%

6,652,013

FMR LLC

$293,823,250

9.49%

5,322,885

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Fidelity Management & Research Co LLC joint	4,865,366	$268,568,202	91.4%	Defined
STRATEGIC ADVISERS LLC	37	$2,042	0.0%	Defined
Fidelity Institutional Asset Management Trust Co	193,127	$10,660,610	3.6%	Defined
FIAM LLC	264,355	$14,592,396	5.0%	Defined

WELLINGTON MANAGEMENT GROUP LLP

$274,759,267

8.88%

4,977,523

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Wellington Management Company LLP	3,962,654	$218,738,500	79.6%	Defined
Wellington Managment Canada LLC	73,291	$4,045,663	1.5%	Defined
Wellington Management Singapore Pte. Ltd.	63,599	$3,510,664	1.3%	Defined
Wellington Management International Ltd	122,115	$6,740,748	2.5%	Defined
Wellington Trust Company, NA joint	719,637	$39,723,962	14.5%	Defined
Wellington Management Australia Pty Ltd	7,927	$437,570	0.2%	Defined
Wellington Management Europe GmbH	28,300	$1,562,160	0.6%	Defined

NEA Management Company, LLC

$199,519,627

6.45%

3,614,486

ORBIMED ADVISORS LLC

$189,266,227

6.12%

3,428,736

BlackRock, Inc.

$183,466,690

5.93%

3,323,672

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
BLACKROCK FINANCIAL MANAGEMENT INC/DE	50,843	$2,806,533	1.5%	Sole
BlackRock Asset Management Canada Ltd	206	$11,371	0.0%	Sole
BlackRock Investment Management, LLC	113,288	$6,253,497	3.4%	Sole
BLACKROCK ADVISORS LLC	569,998	$31,463,889	17.1%	Sole
BlackRock Fund Advisors	1,544,143	$85,236,693	46.5%	Sole
BlackRock Institutional Trust Company, N.A.	864,201	$47,703,895	26.0%	Sole
BlackRock Investment Management (UK) Ltd.	61,449	$3,391,984	1.8%	Sole
BlackRock Asset Management Ireland Ltd	54,551	$3,011,215	1.6%	Sole
BlackRock (Luxembourg) S.A.	2,071	$114,319	0.1%	Sole
BlackRock Asset Management Schweiz AG	3,807	$210,146	0.1%	Sole
Aperio Group, LLC	59,115	$3,263,148	1.8%	Sole

Paradigm Biocapital Advisors LP

$138,442,428

4.47%

2,508,015

NVP ASSOCIATES, LLC

$117,925,692

3.81%

2,136,335

Deep Track Capital, LP

$95,637,808

3.09%

1,732,569

Polar Capital Holdings Plc

$88,789,972

2.87%

1,608,514

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Polar Capital LLP	1,608,514	$88,789,972	100.0%	Defined

VANGUARD CAPITAL MANAGEMENT LLC

$81,551,817

2.63%

1,477,388

Aaron Wealth Advisors LLC

$64,462,504

2.08%

1,167,799

Driehaus Capital Management LLC

$58,323,160

1.88%

1,056,579

Kynam Capital Management, LP

$51,600,904

1.67%

934,799

Woodline Partners LP

$49,685,078

1.61%

900,092

EVENTIDE ASSET MANAGEMENT, LLC

$48,216,758

1.56%

873,492

STATE STREET CORP

$47,718,523

1.54%

864,466

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
STATE STREET GLOBAL ADVISORS EUROPE LIMITED joint	864,466	$47,718,523	100.0%	Defined

PRICE T ROWE ASSOCIATES INC /MD/

$44,977,346

1.45%

814,807

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
T. Rowe Price International Ltd	64,632	$3,567,686	7.9%	Defined
Held directly	750,175	$41,409,660	92.1%	Sole

Parkman Healthcare Partners LLC

$44,169,549

1.43%

800,173

GEODE CAPITAL MANAGEMENT, LLC

$42,673,574

1.38%

773,072

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
GEODE CAPITAL MANAGEMENT TRUST COMPANY, LLC	105,202	$5,807,150	13.6%	Defined
Held directly	667,870	$36,866,424	86.4%	Defined

BRAIDWELL LP

$39,240,576

1.27%

710,880

TCG Crossover Management, LLC

$35,880,000

1.16%

650,000

Cormorant Asset Management, LP

$30,360,000

0.98%

550,000

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Chen Bihua	550,000	$30,360,000	100.0%	Defined

Soleus Capital Management, L.P.

$28,443,400

0.92%

515,279

GOLDMAN SACHS GROUP INC

$25,337,076

0.82%

459,005

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
GOLDMAN SACHS & CO. LLC	383,185	$21,151,812	83.5%	Defined
GOLDMAN SACHS ASSET MANAGEMENT, L.P.	75,820	$4,185,264	16.5%	Defined

MARSHALL WACE, LLP

$22,184,052

0.72%

401,885

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Marshall Wace North America L.P. joint	401,885	$22,184,052	100.0%	Other

EcoR1 Capital, LLC

$21,445,200

0.69%

388,500

VANGUARD PORTFOLIO MANAGEMENT LLC

$19,138,778

0.62%

346,717

BANK OF AMERICA CORP /DE/

$16,500,769

0.53%

298,927

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
BANK OF AMERICA NA	287,524	$15,871,324	96.2%	Defined
BOFA SECURITIES, INC.	11,403	$629,445	3.8%	Defined

Rock Springs Capital Management LP

$16,461,633

0.53%

298,218

Candriam S.C.A.

$16,002,093

0.52%

289,893

UBS Group AG

$15,055,633

0.49%

272,747

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
UBS Financial Services Inc	4,778	$263,745	1.8%	Defined
UBS AG	267,969	$14,791,888	98.2%	Defined

Opaleye Management Inc.

$14,352,000

0.46%

260,000

FRANKLIN RESOURCES INC

$13,947,107

0.45%

252,665

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
FIDUCIARY TRUST INTERNATIONAL LLC	64	$3,532	0.0%	Defined
FRANKLIN ADVISERS INC	252,601	$13,943,575	100.0%	Defined

Schonfeld Strategic Advisors LLC

$13,726,584

0.44%

248,670

MORGAN STANLEY

$13,720,399

0.44%

248,558

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
MORGAN STANLEY & CO INTERNATIONAL PLC	203	$11,205	0.1%	Defined
MORGAN STANLEY & CO. LLC	16,491	$910,303	6.6%	Defined
MORGAN STANLEY CAPITAL SERVICES, LLC	172,148	$9,502,569	69.3%	Defined
MORGAN STANLEY SMITH BARNEY LLC	15	$828	0.0%	Defined
PARAMETRIC PORTFOLIO ASSOCIATES LLC	13	$717	0.0%	Defined
Eaton Vance Advisers International Ltd	59,688	$3,294,777	24.0%	Defined

NORTHERN TRUST CORP

$13,616,623

0.44%

246,678

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
NORTHERN TRUST CO joint	238,251	$13,151,454	96.6%	Defined
NORTHERN TRUST GLOBAL INVESTMENTS LTD	3,648	$201,369	1.5%	Defined
DWS INVESTMENT MANAGEMENT AMERICAS, INC joint	4,779	$263,800	1.9%	Other

DIMENSIONAL FUND ADVISORS LP

$12,900,239

0.42%

233,700

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
DFA Australia Ltd.	1,693	$93,453	0.7%	Defined
Dimensional Ireland Ltd	5,062	$279,422	2.2%	Defined
Held directly	226,945	$12,527,364	97.1%	Sole

CHARLES SCHWAB INVESTMENT MANAGEMENT INC

$12,866,844

0.42%

233,095

MILLENNIUM MANAGEMENT LLC

$12,483,535

0.40%

226,151

Tetragon Partners GP Ltd

$11,235,573

0.36%

203,543

VANGUARD FIDUCIARY TRUST CO

$11,118,880

0.36%

201,429

Caligan Partners LP

$11,040,000

0.36%

200,000

Caption Management, LLC

$11,040,000

0.36%

200,000

Caption Management, LLC

$11,040,000

0.36%

200,000

D. E. Shaw & Co., Inc.

$10,088,738

0.33%

182,767

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
D. E. SHAW & CO, L.P.	182,767	$10,088,738	100.0%	Defined

JPMORGAN CHASE & CO

$7,706,527

0.25%

139,611

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
JPMorgan Chase Bank, N.A.	20,515	$1,132,428	14.7%	Defined
J.P. Morgan Investment Management Inc.	115,615	$6,381,948	82.8%	Defined
J.P. Morgan Securities plc	3,481	$192,151	2.5%	Defined

KVP Capital Advisors, LP

$6,708,124

0.22%

121,524

TWO SIGMA INVESTMENTS, LP

$6,263,820

0.20%

113,475

Burkehill Global Management, LP

$5,520,000

0.18%

100,000

Nuveen, LLC

$5,450,060

0.18%

98,733

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Nuveen Asset Management, LLC joint	5,868	$323,913	5.9%	Defined
TIAA CREF INVESTMENT MANAGEMENT LLC joint	322	$17,774	0.3%	Defined
TEACHERS ADVISORS, LLC joint	92,543	$5,108,373	93.7%	Defined

TD Asset Management Inc

$5,277,009

0.17%

95,598

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$5,210,880

0.17%

94,400

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	94,400	$5,210,880	100.0%	Other

Elmind Capital, LP

$5,023,200

0.16%

91,000

Bank of New York Mellon Corp

$4,908,769

0.16%

88,927

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Mellon Investments Corporation	29,492	$1,627,958	33.2%	Defined
The Bank of New York Mellon	59,053	$3,259,725	66.4%	Defined
BNY Mellon, NA joint	380	$20,976	0.4%	Defined
Held directly	2	$110	0.0%	Defined

PRUDENTIAL FINANCIAL INC

$4,860,084

0.16%

88,045

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
PGIM Quantitative Solutions LLC	66,745	$3,684,324	75.8%	Defined
Prudential Trust Co	21,300	$1,175,760	24.2%	Defined

BARCLAYS PLC

$4,849,540

0.16%

87,854

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
BARCLAYS BANK PLC	86,149	$4,755,424	98.1%	Defined
BARCLAYS CAPITAL INC.	1,705	$94,116	1.9%	Defined

Affinity Asset Advisors, LLC

$4,140,000

0.13%

75,000

PFM Health Sciences, LP

$3,917,599

0.13%

70,971

BOOTHBAY FUND MANAGEMENT, LLC

$3,883,485

0.13%

70,353

MANUFACTURERS LIFE INSURANCE COMPANY, THE

$3,649,382

0.12%

66,112

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
MANULIFE FINANCIAL CORP joint	66,112	$3,649,382	100.0%	Defined

MOORE CAPITAL MANAGEMENT, LP

$3,582,093

0.12%

64,893

Rhenman & Partners Asset Management AB

$3,422,400

0.11%

62,000

Invesco Ltd.

$2,797,424

0.09%

50,678

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Invesco Advisers, Inc. joint	4,725	$260,819	9.3%	Defined
Invesco Trust Co joint	12,301	$679,015	24.3%	Defined
Invesco Capital Management LLC	33,652	$1,857,590	66.4%	Defined

ALPS ADVISORS INC

$2,650,262

0.09%

48,012

PLATINUM INVESTMENT MANAGEMENT LTD

$2,406,554

0.08%

43,597

Swiss National Bank

$2,368,080

0.08%

42,900

Ensign Peak Advisors, Inc

$2,327,011

0.08%

42,156

ALGERT GLOBAL LLC

$2,322,264

0.08%

42,070

Creative Planning

$2,181,724

0.07%

39,524

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
CREATIVE PLANNING TRUST Co LLC	692	$38,198	1.8%	Defined
Held directly	38,832	$2,143,526	98.2%	Sole

JANE STREET GROUP, LLC

$2,075,520

0.07%

37,600

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Jane Street Capital, LLC	37,600	$2,075,520	100.0%	Defined

RHUMBLINE ADVISERS

$2,053,219

0.07%

37,196

DEUTSCHE BANK AG\

$1,749,452

0.06%

31,693

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
DWS INVESTMENT MANAGEMENT AMERICAS, INC	584	$32,236	1.8%	Defined
DWS Investments UK Ltd	31,109	$1,717,216	98.2%	Defined

ALLIANCEBERNSTEIN L.P.

$1,711,200

0.06%

31,000

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Equitable Holdings, Inc.	31,000	$1,711,200	100.0%	Defined

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$1,711,200

0.06%

31,000

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	31,000	$1,711,200	100.0%	Other

WELLS FARGO & COMPANY/MN

$1,562,877

0.05%

28,313

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
WELLS FARGO BANK N A	28,313	$1,562,877	100.0%	Defined

EXCHANGE TRADED CONCEPTS, LLC

$1,513,639

0.05%

27,421

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Roundhill Financial Inc.	27,421	$1,513,639	100.0%	Other

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$1,472,956

0.05%

26,684

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	26,684	$1,472,956	100.0%	Other

VOYA INVESTMENT MANAGEMENT LLC

$1,442,486

0.05%

26,132

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Voya Investment Management Co. LLC joint	26,132	$1,442,486	100.0%	Defined

Universal- Beteiligungs- und Servicegesellschaft mbH

$1,424,160

0.05%

25,800

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Universal-Investment-Gesellschaft mbH	25,800	$1,424,160	100.0%	Defined

TEACHERS RETIREMENT SYSTEM OF THE STATE OF KENTUCKY

$1,400,810

0.05%

25,377

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
WELLINGTON SMALL CAP EQUITY	25,377	$1,400,810	100.0%	Sole

CITIGROUP INC

$1,386,734

0.04%

25,122

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Citigroup Financial Products Inc. joint	25,122	$1,386,734	100.0%	Defined

CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM

$1,290,355

0.04%

23,376

AMERICAN CENTURY COMPANIES INC

$1,251,936

0.04%

22,680

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
AMERICAN CENTURY INVESTMENT MANAGEMENT INC	22,680	$1,251,936	100.0%	Defined

AQR CAPITAL MANAGEMENT LLC

$1,247,021

0.04%

22,591

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
RF&L WEALTH MANAGEMENT, LLC	5	$276	0.0%	Other
Compound Planning, Inc.	5	$276	0.0%	Other
Arax Advisory Partners	262	$14,462	1.2%	Other
HALBERT HARGROVE GLOBAL ADVISORS, LLC	189	$10,432	0.8%	Other
Stokes Family Office, LLC	119	$6,568	0.5%	Other
Held directly	22,011	$1,215,007	97.4%	Defined

CITADEL ADVISORS LLC

$1,236,480

0.04%

22,400

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Citadel Securities GP LLC	22,400	$1,236,480	100.0%	Defined

Legal & General Group Plc

$1,191,381

0.04%

21,583

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Legal & General Investment Management America Inc	3,013	$166,317	14.0%	Defined
Legal & General Investment Management Ltd joint	18,570	$1,025,064	86.0%	Defined

UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC

$1,178,188

0.04%

21,344

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
UBS Group AG	338	$18,657	1.6%	Defined
UBS Asset Management Switzerland AG	21,006	$1,159,531	98.4%	Defined

Cerity Partners LLC

$1,159,034

0.04%

20,997

Vanguard Global Advisers, LLC

$1,047,088

0.03%

18,969

MetLife Investment Management, LLC

$1,007,400

0.03%

18,250

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
METLIFE INC	18,250	$1,007,400	100.0%	Defined

Russell Investments Group, Ltd.

$1,002,541

0.03%

18,162

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Russell Investment Management, LLC	16,333	$901,581	89.9%	Defined
Russell Investments Capital, LLC	1,829	$100,960	10.1%	Defined

Koa Wealth Management, LLC

$944,637

0.03%

17,113

STATE OF WISCONSIN INVESTMENT BOARD

$881,599

0.03%

15,971

VANGUARD ASSET MANAGEMENT, Ltd

$814,310

0.03%

14,752

Optimize Financial Inc

$798,081

0.03%

14,458

Sound Capital Solutions LLC

$798,081

0.03%

14,458

MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd.

$788,918

0.03%

14,292

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Global X Management CO LLC joint	14,292	$788,918	100.0%	Defined

DAFNA Capital Management LLC

$651,856

0.02%

11,809

HighVista Strategies LLC

$642,196

0.02%

11,634

Key facts CIK 1776111 CUSIP 55287L101 13F (30d) 101 filings 101 filers Visit website Investor relations