Vault-13

MBX BIOSCIENCES INC MBX

COM · Common Stock · CUSIP 55287L101

89 institutional holders +9 vs Q1 2025
36,872,65736.9m shares reported held*
109.8% of all shares outstanding*
$420.7mreported value*
20 new 40 added 14 reduced 12 sold out net bought ≈ $13.8m (+1.2m shares)

* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($24.5k this quarter). Holder counts are more reliable. Shares outstanding: 33.6m as of 2025-08-04, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $11.41. Options: 4 managers hold calls ($848.2k notional), 4 hold puts ($1.6m).

Trends to Q2 2025

Institutional holders

Managers reporting a position, each quarter

050100Q3 24: 46Q4 24: 64Q1 25: 80Q2 25: 8989Q3 24Q4 24Q1 25Q2 25
Numbers
QuarterHolders
Q3 202446
Q4 202464
Q1 202580
Q2 202589

Buyers vs sellers

Managers adding to or starting a position, vs cutting or selling out

Bought or addedCut or sold out
1000100Q4 24: 42 bought or addedQ4 24: 21 cut or sold outQ4 24Q1 25: 49 bought or addedQ1 25: 23 cut or sold outQ1 25Q2 25: 60 bought or addedQ2 25: 26 cut or sold outQ2 25
Numbers
QuarterBought or addedCut or sold out
Q4 20244221
Q1 20254923
Q2 20256026

Calls vs puts

Options held, notional value, last 4 quarters. P/C = puts ÷ calls

CallsPuts
$0$500k$1m$1.5m$2mQ3 24 calls: $0Q3 24 puts: $0Q3 24P/C —Q4 24 calls: $0Q4 24 puts: $0Q4 24P/C —Q1 25 calls: $0Q1 25 puts: $0Q1 25P/C —Q2 25 calls: $848.2kQ2 25 puts: $1.6mQ2 25P/C 1.92
Numbers
QuarterCallsPutsP/C
Q3 2024$0$0—
Q4 2024$0$0—
Q1 2025$0$0—
Q2 2025$848.2k$1.6m1.92

Biggest buyers

Point72 Asset Management, L.P. Added +863,305+863.3k
MILLENNIUM MANAGEMENT LLC Added +596,400+596.4k
Parkman Healthcare Partners LLC Added +543,610+543.6k
Schonfeld Strategic Advisors LLC Added +430,771+430.8k
VANGUARD GROUP INC Added +378,121+378.1k
PRICE T ROWE ASSOCIATES INC /MD/ Added +245,994+246.0k
Sio Capital Management, LLC New +241,000+241.0k
BlackRock, Inc. Added +228,504+228.5k
SECTORAL ASSET MANAGEMENT INC New +191,825+191.8k
MPM BIOIMPACT LLC Added +161,466+161.5k

Biggest sellers

RA CAPITAL MANAGEMENT, L.P. Reduced -1,133,493-1.1m
Deep Track Capital, LP Reduced -830,343-830.3k
WELLINGTON MANAGEMENT GROUP LLP Reduced -371,893-371.9k
JPMORGAN CHASE & CO Reduced -193,051-193.1k
Affinity Asset Advisors, LLC Sold out -175,000-175.0k
MARSHALL WACE, LLP Sold out -111,211-111.2k
EcoR1 Capital, LLC Reduced -109,479-109.5k
CITIGROUP INC Reduced -91,605-91.6k
MORGAN STANLEY Reduced -90,602-90.6k
PLATINUM INVESTMENT MANAGEMENT LTD Reduced -73,189-73.2k

Biggest calls

MILLENNIUM MANAGEMENT LLC New $585.3k51.3k shares
SUSQUEHANNA INTERNATIONAL GROUP, LLP New $257.9k22.6k shares
SIMPLEX TRADING, LLC New $5.0k500 shares
CONCOURSE FINANCIAL GROUP SECURITIES, INC. New $00 shares

Biggest puts

SIMPLEX TRADING, LLC New $745.0k65.3k shares
SUSQUEHANNA INTERNATIONAL GROUP, LLP New $645.8k56.6k shares
CITADEL ADVISORS LLC New $236.2k20.7k shares
CONCOURSE FINANCIAL GROUP SECURITIES, INC. New $00 shares

Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.

Major shareholders (over 5%)

Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.

HolderStakeChangeShares Last filed
Frazier Life Sciences Public Fund, L.P. 13D · may seek influence no change · filed 2026-08-10
Stated purposeItem 4 is hereby amended to remove references to "FLSPOF" and the "FLSPOF Shares" from the first paragraph. Full filing
11.7% no change 5.2m≈ $289.4m 2026-08-10
FMR LLC 13G · institution +5.0 pts · filed 2026-07-08 11.2% +5.0 pts 5.3m≈ $293.8m 2026-07-08
WELLINGTON MANAGEMENT GROUP LLP 13G · institution +3.0 pts · filed 2026-07-08 10.5% +3.0 pts 5.0m≈ $274.8m 2026-07-08
New Enterprise Associates 17, L.P. 13D · may seek influence filed 2025-11-10
Stated purposeNEA 17 acquired the NEA 17 Shares for investment purposes. Depending on market conditions, its continuing evaluation of the business and prospects of the Issuer and other factors, NEA 17 and the other Reporting Persons may dispose of or acquire additional shares of the Issuer. Except as set forth above, none of the Reporting Persons has any present plans which relate to or would result in: (a) The acquisition by any person of additional securities of the Issuer, or the disposition of securities of the Issuer; (b) An extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of its subsidiaries; (c) A sale or transfer of a material amount of assets of the Issuer or any of its subsidiaries; (d) Any change in the present board of dire… Full filing
8.1% 3.6m≈ $199.8m 2025-11-10
ORBIMED ADVISORS LLC 13D · may seek influence -1.3 pts · filed 2026-08-10
Stated purposeThe Reporting Persons from time to time intend to review their investment in the Issuer on the basis of various factors, including the Issuer's business, financial condition, results of operations and prospects, general economic and industry conditions, the securities markets in general and those for the Issuer's Shares in particular, as well as other developments and other investment opportunities. Based upon such review, the Reporting Persons will take such actions in the future as the Reporting Persons may deem appropriate in light of the circumstances existing from time to time. If the Reporting Persons believe that further investment in the Issuer is attractive, whether because of the market price of Shares or otherwise, they may acquire Shares or other securities of the Issuer either… Full filing
6.4% -1.3 pts 3.1m≈ $169.7m 2026-08-10
BlackRock, Inc. 13G · institution +0.7 pts · filed 2026-07-29 5.5% +0.7 pts 2.6m≈ $145.1m 2026-07-29
Paradigm Biocapital Advisors LP 13G · passive investor new · filed 2026-06-24 5.2% new 2.5m≈ $137.6m 2026-06-24

Fell to 5% or below in the last year: Deep Track Capital, LP (3.6%, 2026-08-14), Hawryluk P. Kent (4.3%, 2025-11-14)

Insider purchases and sales in Q2 2025

Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.

Officers and directors buying vs selling

Number of people, by quarter (10% owners not included)

BuyingSelling
505Q3 23: 0 buyingQ3 23: 0 sellingQ4 23: 0 buyingQ4 23: 0 sellingQ4 23Q1 24: 0 buyingQ1 24: 0 sellingQ2 24: 0 buyingQ2 24: 0 sellingQ2 24Q3 24: 5 buyingQ3 24: 0 sellingQ4 24: 0 buyingQ4 24: 0 sellingQ4 24Q1 25: 3 buyingQ1 25: 0 sellingQ2 25: 1 buyingQ2 25: 0 sellingQ2 25
Numbers
QuarterBuyingBoughtSellingSoldSold under a plan
Q3 20230—0——
Q4 20230—0——
Q1 20240—0——
Q2 20240—0——
Q3 20245$34.0m0——
Q4 20240—0——
Q1 20253$2.6m0——
Q2 20251$45.3k0——
DateInsiderTradeSharesPrice ValueTheir holding
2025-04-08 Pescovitz Ora H. Director Bought 7,693 $5.89 $45.3k7.7k shares +46%

Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).

Holders, Q2 2025

#ManagerLocationShares Value% of their portfolioChangeShares change
1 Frazier Life Sciences Management, L.P. 2.73% of their portfolio PALO ALTO, CA 5,985,3476.0m $68.3m $68.3m 2.73% Unchanged
2 ORBIMED ADVISORS LLC 1.15% of their portfolio New York, NY 4,002,8874.0m $45.7m $45.7m 1.15% Unchanged
3 NEA Management Company, LLC 3.10% of their portfolio TIMONIUM, MD 3,614,4863.6m $41.2m $41.2m 3.10% Unchanged
4 WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio Boston, MA 2,266,6282.3m $25.9m $25.9m 0.00% Reduced -371.9k -371,893
5 Deep Track Capital, LP 0.80% of their portfolio GREENWICH, CT 2,188,5922.2m $25.0m $25.0m 0.80% Reduced -830.3k -830,343
6 NVP ASSOCIATES, LLC 13.24% of their portfolio MENLO PARK, CA 2,136,3352.1m $24.4m $24.4m 13.24% Unchanged
7 Driehaus Capital Management LLC 0.14% of their portfolio Chicago, IL 1,571,9061.6m $17.9m $17.9m 0.14% Reduced -7.3k -7,301
8 PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio BALTIMORE, MD 1,346,9101.3m $15.4m $15.4m 0.00% Added +246.0k +245,994
9 MPM BIOIMPACT LLC 2.56% of their portfolio BOSTON, MA 1,294,4161.3m $14.8m $14.8m 2.56% Added +161.5k +161,466
10 EcoR1 Capital, LLC 0.78% of their portfolio San Francisco, CA 1,149,7941.1m $13.1m $13.1m 0.78% Reduced -109.5k -109,479
11 VANGUARD GROUP INC 0.00% of their portfolio Valley Forge, PA 1,043,6841.0m $11.9m $11.9m 0.00% Added +378.1k +378,121
12 BlackRock, Inc. 0.00% of their portfolio New York, NY 1,011,5461.0m $11.5m $11.5m 0.00% Added +228.5k +228,504
13 Point72 Asset Management, L.P. 0.03% of their portfolio STAMFORD, CT 973,787973.8k $11.1m $11.1m 0.03% Added +863.3k +863,305
14 Woodline Partners LP 0.05% of their portfolio San Francisco, CA 901,103901.1k $10.3m $10.3m 0.05% Added +23.6k +23,642
15 Parkman Healthcare Partners LLC 1.15% of their portfolio STAMFORD, CT 871,933871.9k $9.9m $9.9m 1.15% Added +543.6k +543,610
16 MILLENNIUM MANAGEMENT LLC 0.01% of their portfolio NEW YORK, NY 766,840766.8k $8.7m $8.7m 0.01% Added +596.4k +596,400
17 Cormorant Asset Management, LP 0.59% of their portfolio BOSTON, MA 700,000700.0k $8.0m $8.0m 0.59% Unchanged
18 TCG Crossover Management, LLC 0.85% of their portfolio PALO ALTO, CA 650,000650.0k $7.4m $7.4m 0.85% Unchanged
19 Schonfeld Strategic Advisors LLC 0.05% of their portfolio NEW YORK, NY 631,413631.4k $7.2m $7.2m 0.05% Added +430.8k +430,771
20 FRANKLIN RESOURCES INC 0.00% of their portfolio San Mateo, CA 494,852494.9k $5.6m $5.6m 0.00% Added +125.5k +125,537
21 RA CAPITAL MANAGEMENT, L.P. 0.07% of their portfolio BOSTON, MA 377,841377.8k $4.3m $4.3m 0.07% Reduced -1.1m -1,133,493
22 GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio BOSTON, MA 348,447348.4k $4.0m $4.0m 0.00% Added +74.0k +73,989
23 STATE STREET CORP 0.00% of their portfolio BOSTON, MA 265,119265.1k $3.0m $3.0m 0.00% Added +87.9k +87,899
24 Sio Capital Management, LLC 1.10% of their portfolio NEW YORK, NY 241,000241.0k $2.7m $2.7m 1.10% New
25 Opaleye Management Inc. 0.55% of their portfolio BOSTON, MA 239,319239.3k $2.7m $2.7m 0.55% Reduced -10.7k -10,681
26 SECTORAL ASSET MANAGEMENT INC 1.45% of their portfolio MONTREAL, A8 191,825191.8k $2.2m $2.2m 1.45% New
27 TD Asset Management Inc 0.00% of their portfolio Toronto, A6 171,304171.3k $2.0m $2.0m 0.00% Added +19.8k +19,800
28 STEMPOINT CAPITAL LP 0.52% of their portfolio NEW YORK, NY 141,021141.0k $1.6m $1.6m 0.52% Added +44.4k +44,406
29 NORTHERN TRUST CORP 0.00% of their portfolio CHICAGO, IL 115,594115.6k $1.3m $1.3m 0.00% Added +19.1k +19,087
30 PLATINUM INVESTMENT MANAGEMENT LTD 0.09% of their portfolio SYDNEY AUSTRALIA 2000, C3 112,743112.7k $1.3m $1.3m 0.09% Reduced -73.2k -73,189
31 CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio SAN FRANCISCO, CA 107,483107.5k $1.2m $1.2m 0.00% Added +12.9k +12,937
32 MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio Toronto, A6 87,09787.1k $993.8k $993.8k 0.00% Added +37.0k +36,987
33 Walleye Capital LLC 0.01% of their portfolio NEW YORK, NY 70,33370.3k $802.5k $802.5k 0.01% Added +37.8k +37,843
34 Rockefeller Capital Management L.P. 0.00% of their portfolio NEW YORK, NY 68,27068.3k $779.0k $779.0k 0.00% New
35 Exome Asset Management LLC 0.61% of their portfolio NEW YORK, NY 63,07663.1k $719.7k $719.7k 0.61% Reduced -70.0k -70,037
36 FMR LLC 0.00% of their portfolio BOSTON, MA 61,33361.3k $699.8k $699.8k 0.00% Added +17.1k +17,093
37 BARCLAYS PLC 0.00% of their portfolio LONDON, X0 58,54158.5k $668.0k $668.0k 0.00% Added +46.7k +46,723
38 Aaron Wealth Advisors LLC 0.06% of their portfolio Chicago, IL 50,00050.0k $570.5k $570.5k 0.06% Unchanged
39 Resolute Capital Asset Partners LLC 0.30% of their portfolio DENVER, CO 49,67049.7k $566.7k $566.7k 0.30% New
40 BANK OF AMERICA CORP /DE/ 0.00% of their portfolio CHARLOTTE, NC 42,38742.4k $483.6k $483.6k 0.00% Added +14.3k +14,297
41 Bank of New York Mellon Corp 0.00% of their portfolio NEW YORK, NY 38,03238.0k $433.9k $433.9k 0.00% Added +14.1k +14,122
42 Koa Wealth Management, LLC 0.29% of their portfolio Encinitas, CA 31,75231.8k $362.3k $362.3k 0.29% Added +12.4k +12,356
43 UBS Group AG 0.00% of their portfolio ZURICH, V8 30,96731.0k $353.3k $353.3k 0.00% Added +3.5k +3,468
44 BRIDGEWAY CAPITAL MANAGEMENT, LLC 0.01% of their portfolio HOUSTON, TX 29,20029.2k $333.2k $333.2k 0.01% New
45 SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio BALA CYNWYD, PA 27,63227.6k $315.3k $315.3k 0.00% Added +14.0k +13,972
46 MORGAN STANLEY 0.00% of their portfolio NEW YORK, NY 24,00824.0k $273.9k $273.9k 0.00% Reduced -90.6k -90,602
47 RHUMBLINE ADVISERS 0.00% of their portfolio BOSTON, MA 23,66223.7k $270.0k $270.0k 0.00% Added +14.9k +14,950
48 Nuveen, LLC 0.00% of their portfolio CHARLOTTE, NC 22,14322.1k $252.7k $252.7k 0.00% Added +7.7k +7,672
49 ALPS ADVISORS INC 0.00% of their portfolio Denver, CO 18,04818.0k $205.9k $205.9k 0.00% Reduced -8.0k -7,986
50 AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio Greenwich, CT 18,00118.0k $205.4k $205.4k 0.00% New
51 PRELUDE CAPITAL MANAGEMENT, LLC 0.02% of their portfolio NEW YORK, NY 15,61715.6k $178.2k $178.2k 0.02% Reduced -24.6k -24,608
52 INTECH INVESTMENT MANAGEMENT LLC 0.00% of their portfolio WEST PALM BEACH, FL 14,27114.3k $162.8k $162.8k 0.00% Added +3.5k +3,543
53 XTX Topco Ltd 0.01% of their portfolio LONDON, X0 11,86111.9k $135.3k $135.3k 0.01% New
54 MetLife Investment Management, LLC 0.00% of their portfolio Whippany, NJ 11,01811.0k $125.7k $125.7k 0.00% New
55 WELLS FARGO & COMPANY/MN 0.00% of their portfolio SAN FRANCISCO, CA 10,94310.9k $124.9k $124.9k 0.00% Added +5.0k +4,966
56 ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio NASHVILLE, TN 10,50010.5k $119.8k $119.8k 0.00% New
57 MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio CAUSEWAY BAY, K3 9,3299.3k $106.4k $106.4k 0.00% Added +2.7k +2,682
58 Virtus Investment Advisers, LLC 0.03% of their portfolio HARTFORD, CT 8,7728.8k $100.1k $100.1k 0.03% Added +766 +766
59 DEUTSCHE BANK AG\ 0.00% of their portfolio FRANKFURT AM MAIN, 2M 8,7628.8k $100.0k $100.0k 0.00% Unchanged
60 JPMORGAN CHASE & CO 0.00% of their portfolio NEW YORK, NY 8,1848.2k $93.4k $93.4k 0.00% Reduced -193.1k -193,051
61 Quarry LP 0.02% of their portfolio NEW YORK, NY 8,0008.0k $91.3k $91.3k 0.02% New
62 CITIGROUP INC 0.00% of their portfolio NEW YORK, NY 5,7235.7k $65.3k $65.3k 0.00% Reduced -91.6k -91,605
63 NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio ALBANY, NY 4,3004.3k $49.1k $49.1k 0.00% Unchanged
64 ROYAL BANK OF CANADA 0.00% of their portfolio TORONTO, A6 2,5962.6k $30.0k $30.0k 0.00% Added +2.0k +1,961
65 Police & Firemen's Retirement System of New Jersey 0.00% of their portfolio TRENTON, NJ 2,1432.1k $24.5k $24.5k 0.00% Unchanged
66 Tower Research Capital LLC (TRC) 0.00% of their portfolio NEW YORK, NY 2,1102.1k $24.1k $24.1k 0.00% Added +745 +745
67 CWM, LLC 0.00% of their portfolio OMAHA, NE 1,8021.8k $21.0k $21.0k 0.00% Added +1.7k +1,665
68 NISA INVESTMENT ADVISORS, LLC 0.00% of their portfolio ST. LOUIS, MO 1,5921.6k $18.2k $18.2k 0.00% New
69 Legal & General Group Plc 0.00% of their portfolio London, X0 1,5511.6k $17.7k $17.7k 0.00% Added +444 +444
70 BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio PARIS, I0 1,3291.3k $15.2k $15.2k 0.00% Reduced -29.6k -29,587
71 Ameritas Investment Partners, Inc. 0.00% of their portfolio LINCOLN, NE 1,1771.2k $13.4k $13.4k 0.00% Unchanged
72 CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio WEST SACRAMENTO, CA 1,0641.1k $12.1k $12.1k 0.00% Added +232 +232
73 RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio ST. PETERSBURG, FL 761761 $8.7k $8.7k 0.00% New
74 STRS OHIO 0.00% of their portfolio COLUMBUS, OH 700700 $8.0k $8.0k 0.00% Unchanged
75 Sterling Capital Management LLC 0.00% of their portfolio CHARLOTTE, NC 460460 $5.2k $5.2k 0.00% Added +369 +369
76 SIMPLEX TRADING, LLC 0.00% of their portfolio CHICAGO, IL 411411 $4.0k $4.0k 0.00% New
77 AMALGAMATED BANK 0.00% of their portfolio NEW YORK, NY 384384 $4.0k $4.0k 0.00% Unchanged
78 US BANCORP \DE\ 0.00% of their portfolio MINNEAPOLIS, MN 337337 $3.8k $3.8k 0.00% Added +7 +7
79 GAMMA Investing LLC 0.00% of their portfolio FOSTER CITY, CA 299299 $3.4k $3.4k 0.00% Added +279 +279
80 Physician Wealth Advisors, Inc. 0.00% of their portfolio MIDVALE, UT 109109 $1.2k $1.2k 0.00% New
81 Parallel Advisors, LLC 0.00% of their portfolio SAN FRANCISCO, CA 108108 $1.2k $1.2k 0.00% New
82 SIGNATUREFD, LLC 0.00% of their portfolio ATLANTA, GA 101101 $1.2k $1.2k 0.00% New
83 Rise Advisors, LLC 0.00% of their portfolio ROCHESTER, NY 6868 $776 $776 0.00% New
84 Russell Investments Group, Ltd. 0.00% of their portfolio Seattle, WA 3535 $399 $399 0.00% New
85 EverSource Wealth Advisors, LLC 0.00% of their portfolio BIRMINGHAM, AL 2929 $331 $331 0.00% Added +20 +20
86 Allworth Financial LP 0.00% of their portfolio FOLSOM, CA 2525 $286 $286 0.00% New
87 ROTHSCHILD INVESTMENT LLC 0.00% of their portfolio CHICAGO, IL 2020 $228 $228 0.00% New
88 Essential Partners LLC 0.00% of their portfolio RANCHO SANTA FE, CA 22 $23 $23 0.00% First filing
89 CONCOURSE FINANCIAL GROUP SECURITIES, INC. — of their portfolio BIRMINGHAM, AL 00 $0 $0 — Unchanged