MBX Biosciences (MBX)
MBX Biosciences on one page: short interest, daily short volume, fails to deliver, planned sales, large holders, 13F holders, earnings dates and insider trades. Listed on Nasdaq, classified by the SEC as pharmaceutical preparations.
4.4M
Short interest
settlement 2026-10-15
7.5
Days to cover
+0.6 days vs prior
63.6%
Short share of volume
2026-11-03
100
Fails to deliver
settlement 2026-09-04
Thu 5 Nov
Next earnings
estimated date
$0
Insider flow, 90 days
0 buys, 0 sells
As of 2026-11-03.
Short interest
FINRA, twice a month. The newest 48 settlements in the table, 48 in the chart. JSONAs of 15 October 2026, short interest in MBX is 4,422,964 shares, up 293,105 shares over the last month. Over the last 48 readings it ranged from 345,329 shares (15 November 2024) to 5,895,340 shares (30 June 2026). At the reported average volume of 593K shares a day that is 7.5 days to cover.
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| Settlement | Shares short | Change | Avg daily volume | Days to cover |
|---|---|---|---|---|
| 2026-10-15 | 4,422,964 | -1.0% | 592,717 | 7.46 |
| 2026-09-30 | 4,466,280 | +8.2% | 653,352 | 6.84 |
| 2026-09-15 | 4,129,859 | -0.6% | 361,137 | 11.44 |
| 2026-08-31 | 4,155,572 | -16.1% | 409,997 | 10.14 |
| 2026-08-14 | 4,950,102 | -4.6% | 442,769 | 11.18 |
| 2026-07-31 | 5,188,562 | -10.2% | 609,309 | 8.52 |
| 2026-07-15 | 5,776,709 | -2.0% | 930,195 | 6.21 |
| 2026-06-30 | 5,895,340 | +3.2% | 1,116,750 | 5.28 |
| 2026-06-15 | 5,710,506 | +18.7% | 960,306 | 5.95 |
| 2026-05-29 | 4,811,025 | +12.3% | 568,896 | 8.46 |
| 2026-05-15 | 4,284,613 | +6.2% | 857,788 | 4.99 |
| 2026-04-30 | 4,033,554 | +6.5% | 420,990 | 9.58 |
| 2026-04-15 | 3,786,542 | +5.4% | 490,818 | 7.71 |
| 2026-03-31 | 3,593,407 | +20.4% | 450,952 | 7.97 |
| 2026-03-13 | 2,983,725 | +24.6% | 596,352 | 5.00 |
| 2026-02-27 | 2,395,339 | +8.7% | 532,466 | 4.50 |
| 2026-02-13 | 2,202,822 | +12.1% | 714,619 | 3.08 |
| 2026-01-30 | 1,965,975 | -14.8% | 641,060 | 3.07 |
| 2026-01-15 | 2,307,824 | -40.0% | 800,131 | 2.88 |
| 2025-12-31 | 3,843,943 | +6.4% | 871,163 | 4.41 |
| 2025-12-15 | 3,611,905 | -11.9% | 832,256 | 4.34 |
| 2025-11-28 | 4,101,744 | -11.4% | 604,673 | 6.78 |
| 2025-11-14 | 4,629,382 | +1.0% | 750,881 | 6.17 |
| 2025-10-31 | 4,581,641 | +17.2% | 963,157 | 4.76 |
| 2025-10-15 | 3,909,541 | +0.2% | 998,549 | 3.92 |
| 2025-09-30 | 3,900,619 | -7.7% | 4,108,084 | 1.00 |
| 2025-09-15 | 4,226,517 | +10.0% | 411,736 | 10.27 |
| 2025-08-29 | 3,843,321 | -5.5% | 239,312 | 16.06 |
| 2025-08-15 | 4,065,622 | -23.9% | 437,080 | 9.30 |
| 2025-07-31 | 5,342,249 | +11.7% | 556,782 | 9.59 |
| 2025-07-15 | 4,782,900 | -3.8% | 342,776 | 13.95 |
| 2025-06-30 | 4,970,524 | +6.8% | 420,059 | 11.83 |
| 2025-06-13 | 4,652,881 | -2.0% | 221,949 | 20.96 |
| 2025-05-30 | 4,745,902 | -10.3% | 256,093 | 18.53 |
| 2025-05-15 | 5,291,252 | -1.7% | 249,449 | 21.21 |
| 2025-04-30 | 5,382,464 | +0.4% | 296,525 | 18.15 |
| 2025-04-15 | 5,358,941 | +5.5% | 420,173 | 12.75 |
| 2025-03-31 | 5,078,957 | +11.2% | 259,190 | 19.60 |
| 2025-03-14 | 4,568,242 | +11.2% | 195,713 | 23.34 |
| 2025-02-28 | 4,109,163 | +11.5% | 194,444 | 21.13 |
| 2025-02-14 | 3,684,875 | +31.6% | 384,533 | 9.58 |
| 2025-01-31 | 2,799,627 | +37.9% | 287,344 | 9.74 |
| 2025-01-15 | 2,030,386 | +21.2% | 288,694 | 7.03 |
| 2024-12-31 | 1,674,966 | +228.1% | 444,385 | 3.77 |
| 2024-12-13 | 510,439 | +5.2% | 176,511 | 2.89 |
| 2024-11-29 | 485,164 | +40.5% | 128,296 | 3.78 |
| 2024-11-15 | 345,329 | -1.5% | 81,535 | 4.24 |
| 2024-10-31 | 350,718 | +12.5% | 94,124 | 3.73 |
Daily short volume
FINRA Reg SHO, the last 30 sessions. JSONAs of 3 November 2026, the short share of MBX volume is 63.6%, up 27.7 points over the last five sessions. Over the last 30 readings it ranged from 22.4% (20 October 2026) to 84.7% (21 October 2026). The latest reading is in line with the 30-session average of 62.9%, on 90K shares reported.
| Date | Short volume | Total volume | Short share | Exempt |
|---|---|---|---|---|
| 2026-11-03 | 57K | 90K | 63.6% | 0 |
| 2026-11-02 | 85K | 105K | 81.1% | 0 |
| 2026-10-30 | 210K | 321K | 65.6% | 0 |
| 2026-10-29 | 68K | 103K | 66.4% | 0 |
| 2026-10-28 | 88K | 108K | 81.9% | 0 |
| 2026-10-27 | 99K | 276K | 35.9% | 0 |
| 2026-10-26 | 176K | 398K | 44.1% | 0 |
| 2026-10-23 | 114K | 236K | 48.4% | 0 |
| 2026-10-22 | 110K | 282K | 38.9% | 0 |
| 2026-10-21 | 137K | 162K | 84.7% | 0 |
| 2026-10-20 | 111K | 497K | 22.4% | 0 |
| 2026-10-19 | 168K | 202K | 82.9% | 0 |
| 2026-10-16 | 261K | 337K | 77.6% | 1 |
| 2026-10-15 | 116K | 177K | 65.8% | 44 |
| 2026-10-14 | 133K | 364K | 36.7% | 0 |
| 2026-10-13 | 104K | 222K | 46.8% | 3 |
| 2026-10-12 | 82K | 135K | 61.2% | 0 |
| 2026-10-09 | 107K | 173K | 61.6% | 0 |
| 2026-10-08 | 105K | 155K | 67.5% | 0 |
| 2026-10-07 | 116K | 154K | 75.5% | 0 |
| 2026-10-06 | 88K | 169K | 52.3% | 20 |
| 2026-10-05 | 113K | 141K | 79.6% | 1 |
| 2026-10-02 | 146K | 263K | 55.6% | 0 |
| 2026-10-01 | 125K | 164K | 76.3% | 40 |
| 2026-09-30 | 106K | 173K | 61.2% | 0 |
| 2026-09-29 | 115K | 138K | 82.9% | 0 |
| 2026-09-28 | 140K | 199K | 70.5% | 380 |
| 2026-09-25 | 154K | 212K | 72.6% | 0 |
| 2026-09-24 | 157K | 321K | 48.9% | 14 |
| 2026-09-23 | 115K | 144K | 79.8% | 0 |
Fails to deliver
SEC, the last 30 settlement dates with a fail. JSONAs of 4 September 2026, the fails-to-deliver balance in MBX is 100 shares, down 3,356 shares over the last settlement date. Over the last 30 readings it ranged from 2 shares (8 July 2026) to 22,137 shares (21 May 2026). The latest reading sits at the bottom of that range.
| Settlement | Shares failed | Price | Value |
|---|---|---|---|
| 2026-09-04 | 100 | $61.42 | $6K |
| 2026-08-27 | 3,456 | $66.76 | $231K |
| 2026-08-17 | 76 | $68.57 | $5K |
| 2026-08-04 | 30 | $64.41 | $2K |
| 2026-07-27 | 2,298 | $62.00 | $142K |
| 2026-07-24 | 3,296 | $63.57 | $210K |
| 2026-07-23 | 300 | $58.30 | $17K |
| 2026-07-22 | 680 | $60.28 | $41K |
| 2026-07-20 | 380 | $62.92 | $24K |
| 2026-07-17 | 798 | $58.32 | $47K |
| 2026-07-16 | 1,724 | $60.68 | $105K |
| 2026-07-15 | 170 | $56.59 | $10K |
| 2026-07-09 | 976 | $61.74 | $60K |
| 2026-07-08 | 2 | $62.00 | $124 |
| 2026-06-30 | 145 | $53.85 | $8K |
| 2026-06-29 | 7,308 | $52.31 | $382K |
| 2026-06-18 | 75 | $41.59 | $3K |
| 2026-06-17 | 3,952 | $40.09 | $158K |
| 2026-06-15 | 720 | $35.51 | $26K |
| 2026-06-11 | 1,853 | $30.99 | $57K |
| 2026-05-21 | 22,137 | $31.43 | $696K |
| 2026-05-18 | 2,197 | $32.45 | $71K |
| 2026-05-13 | 148 | $36.98 | $5K |
| 2026-05-04 | 18 | $29.78 | $536 |
| 2026-04-20 | 2,200 | $33.77 | $74K |
| 2026-03-16 | 487 | $28.00 | $14K |
| 2026-03-13 | 10,711 | $27.95 | $299K |
| 2026-03-12 | 435 | $28.94 | $13K |
| 2026-03-10 | 166 | $27.94 | $5K |
| 2026-03-06 | 191 | $31.44 | $6K |
Insider trades
SEC Form 4, newest first. JSONNo open-market insider trades were reported for MBX in the last 90 days. The most recent filings are listed below. Latest filing: Azoulay Salomon (Chief Medical Officer) on 2026-08-04.
| Date | Insider | Title | Type | Shares | Price | Value | Owned after |
|---|---|---|---|---|---|---|---|
| 2026-08-04 | Azoulay Salomon | Chief Medical Officer | Sell | 370 | $65.77 | $24K | 14K |
| 2026-08-03 | Smither John W | Chief Financial Officer | Grant | 28K | $0.00 | $0 | 28K |
| 2026-08-03 | Hoerter Steven L. | President and CEO | Grant | 71K | $0.00 | $0 | 83K |
| 2026-05-08 | Azoulay Salomon | Chief Medical Officer | Sell | 15K | $38.30 | $575K | 15K |
| 2026-05-08 | Azoulay Salomon | Chief Medical Officer | Exercise or conversion | 15K | $16.00 | $240K | 30K |
| 2026-05-08 | Azoulay Salomon | Chief Medical Officer | Sell | 55K | $38.38 | $2.1M | 15K |
| 2026-05-08 | Azoulay Salomon | Chief Medical Officer | Exercise or conversion | 55K | $10.46 | $575K | 70K |
| 2026-05-06 | Hawryluk P. Kent | President & CEO | Sell | 607 | $29.54 | $18K | 728K |
| 2026-05-06 | Azoulay Salomon | Chief Medical Officer | Sell | 231 | $29.54 | $7K | 15K |
| 2026-05-01 | Hoerter Steven L. | Director | Grant | 12K | $0.00 | $0 | 12K |
| 2026-03-13 | Hawryluk P. Kent | President & CEO | Buy | 19K | $28.41 | $526K | 487K |
| 2026-02-26 | Hawryluk P. Kent | President & CEO | Exercise or conversion | 29K | $16.00 | $460K | 728K |
| 2026-02-02 | Hawryluk P. Kent | President & CEO | Grant | 35K | $0.00 | $0 | 700K |
| 2026-02-02 | Bartram Richard | Chief Financial Officer | Grant | 15K | $0.00 | $0 | 15K |
| 2026-02-02 | Azoulay Salomon | Chief Medical Officer | Grant | 15K | $0.00 | $0 | 15K |
| 2025-10-24 | Hawryluk P. Kent | President & CEO | Exercise or conversion | 183K | $3.25 | $594K | 664K |
| 2025-10-20 | Hawryluk P. Kent | President & CEO | Buy | 20K | $13.64 | $273K | 468K |
| 2025-10-17 | Hoerter Steven L. | Director | Buy | 20K | $13.25 | $265K | 20K |
| 2025-09-26 | FHMLS X, L.P. | TenPercentOwner | Buy | 667K | $18.00 | $12.0M | 5.2M |
| 2025-09-26 | Heron Patrick J | Director, 10% owner | Buy | 667K | $18.00 | $12.0M | 5.2M |
| 2025-04-08 | Pescovitz Ora H. | Director | Buy | 8K | $5.89 | $45K | 24K |
| 2025-02-18 | OrbiMed Genesis GP LLC | Director,TenPercentOwner | Buy | 49K | $10.84 | $532K | 3.3M |
| 2025-02-18 | OrbiMed Genesis GP LLC | Director,TenPercentOwner | Buy | 94K | $10.84 | $1.0M | 748K |
| 2025-02-18 | GORDON CARL L | Director,TenPercentOwner | Buy | 94K | $10.84 | $1.0M | 748K |
| 2025-02-18 | GORDON CARL L | Director,TenPercentOwner | Buy | 49K | $10.84 | $532K | 3.3M |
| 2025-02-14 | OrbiMed Genesis GP LLC | Director,TenPercentOwner | Buy | 30K | $9.85 | $291K | 3.2M |
| 2025-02-14 | OrbiMed Genesis GP LLC | Director,TenPercentOwner | Buy | 18K | $9.90 | $178K | 3.2M |
| 2025-02-14 | GORDON CARL L | Director,TenPercentOwner | Buy | 18K | $9.90 | $178K | 3.2M |
| 2025-02-14 | GORDON CARL L | Director,TenPercentOwner | Buy | 30K | $9.85 | $291K | 3.2M |
| 2025-02-04 | Hawryluk P. Kent | President & CEO | Buy | 50K | $10.69 | $535K | 448K |
| 2024-09-16 | Wellington Biomedical Innovation Master Investors (Cayman) II L.P. | TenPercentOwner | Conversion | 404K | price not stated in the filing | not stated | 1.8M |
| 2024-09-16 | Wellington Biomedical Innovation Master Investors (Cayman) II L.P. | TenPercentOwner | Conversion | 1.4M | price not stated in the filing | not stated | 1.4M |
| 2024-09-16 | GORDON CARL L | Director,TenPercentOwner | Conversion | 404K | price not stated in the filing | not stated | 404K |
| 2024-09-16 | GORDON CARL L | Director,TenPercentOwner | Conversion | 2.7M | price not stated in the filing | not stated | 2.7M |
| 2024-09-16 | GORDON CARL L | Director,TenPercentOwner | Buy | 250K | $16.00 | $4.0M | 654K |
| 2024-09-16 | GORDON CARL L | Director,TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.2M |
| 2024-09-16 | Aynechi Tiba | Director | Conversion | 1.4M | price not stated in the filing | not stated | 1.4M |
| 2024-09-16 | Aynechi Tiba | Director | Buy | 750K | $16.00 | $12.0M | 2.1M |
| 2024-09-16 | Hawryluk P. Kent | President & CEO | Conversion | 116K | price not stated in the filing | not stated | 398K |
| 2024-09-16 | Hawryluk P. Kent | President & CEO | Conversion | 284K | price not stated in the filing | not stated | 481K |
| 2024-09-16 | Heron Patrick J | Director,TenPercentOwner | Conversion | 3.9M | price not stated in the filing | not stated | 3.9M |
| 2024-09-16 | Heron Patrick J | Director,TenPercentOwner | Buy | 625K | $16.00 | $10.0M | 4.6M |
| 2024-09-16 | CORNELIUS JAMES M | Director | Conversion | 102K | price not stated in the filing | not stated | 102K |
| 2024-09-16 | FHMLS X, L.P. | TenPercentOwner | Buy | 625K | $16.00 | $10.0M | 4.6M |
| 2024-09-16 | FHMLS X, L.P. | TenPercentOwner | Conversion | 3.9M | price not stated in the filing | not stated | 3.9M |
| 2024-09-16 | NEA Partners 17, L.P. | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | NEA Partners 17, L.P. | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | NEA Partners 17, L.P. | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | ORBIMED ADVISORS LLC | Director,TenPercentOwner | Buy | 250K | $16.00 | $4.0M | 654K |
| 2024-09-16 | ORBIMED ADVISORS LLC | Director,TenPercentOwner | Conversion | 404K | price not stated in the filing | not stated | 404K |
| 2024-09-16 | ORBIMED ADVISORS LLC | Director,TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.2M |
| 2024-09-16 | ORBIMED ADVISORS LLC | Director,TenPercentOwner | Conversion | 2.7M | price not stated in the filing | not stated | 2.7M |
| 2024-09-16 | SANDELL SCOTT D | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | SANDELL SCOTT D | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | SANDELL SCOTT D | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | Yang Rick | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | Yang Rick | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | Yang Rick | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | Walker Paul Edward | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | Walker Paul Edward | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | Walker Paul Edward | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | Makhzoumi Mohamad | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | Makhzoumi Mohamad | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | Makhzoumi Mohamad | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | Florence Anthony A. Jr. | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | Florence Anthony A. Jr. | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | Florence Anthony A. Jr. | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | Chang Carmen | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | Chang Carmen | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | Chang Carmen | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | Behbahani Ali | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | Behbahani Ali | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | Behbahani Ali | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | BASKETT FOREST | TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | BASKETT FOREST | TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
| 2024-09-16 | BASKETT FOREST | TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | Mathers Edward T | Director,TenPercentOwner | Buy | 500K | $16.00 | $8.0M | 3.6M |
| 2024-09-16 | Mathers Edward T | Director,TenPercentOwner | Conversion | 2.1M | price not stated in the filing | not stated | 3.1M |
| 2024-09-16 | Mathers Edward T | Director,TenPercentOwner | Conversion | 1.0M | price not stated in the filing | not stated | 1.0M |
Form 4 filings are due within two business days of the trade. Insiders sell for many reasons that say nothing about the company; open-market buys are rarer.
Planned sales (Form 144)
Newest first. JSON17 Form 144 notices on file for MBX worth $7.8M at the prices reported; 1 in the last 90 days worth $256K. Latest: Hawryluk P. Kent filed on 2026-08-17 to sell 3,745 shares ($256K) from 2026-08-17.
| Filed | Seller | Shares | Market value | Of outstanding | Sale from | Broker |
|---|---|---|---|---|---|---|
| 2026-08-17 | Hawryluk P. KentFormer Officer | 4K | $256K | 0.008% | 2026-08-17 | Fidelity Brokerage Services LLC |
| 2026-08-04 | Hawryluk P. KentOfficer, Director | 936 | $62K | 0.002% | 2026-08-04 | Fidelity Brokerage Services LLC |
| 2026-08-04 | Azoulay SalomonOfficer | 370 | $24K | 0.001% | 2026-08-04 | Fidelity Brokerage Services LLC |
| 2026-06-10 | Bartram RichardFormer Officer | 9K | $280K | 0.019% | 2026-06-10 | Fidelity Brokerage Services LLC |
| 2026-06-09 | Bartram RichardFormer Officer | 11K | $321K | 0.023% | 2026-06-09 | Fidelity Brokerage Services LLC |
| 2026-05-13 | Bartram RichardFormer Officer | 15K | $554K | 0.032% | 2026-05-13 | Fidelity Brokerage Services LLC |
| 2026-05-11 | Bartram RichardFormer Officer | 23K | $992K | 0.047% | 2026-05-11 | Fidelity Brokerage Services LLC |
| 2026-05-08 | Bartram RichardFormer Officer | 10K | $380K | 0.021% | 2026-05-08 | Fidelity Brokerage Services LLC |
| 2026-05-08 | Azoulay SalomonOfficer | 70K | $2.7M | 0.147% | 2026-05-08 | Fidelity Brokerage Services LLC |
| 2026-05-07 | Bartram RichardFormer Officer | 10K | $322K | 0.021% | 2026-05-07 | Fidelity Brokerage Services LLC |
| 2026-05-06 | Hawryluk P. KentOfficer, Director | 607 | $18K | 0.001% | 2026-05-06 | Fidelity Brokerage Services LLC |
| 2026-05-06 | Azoulay SalomonOfficer | 231 | $7K | 0.000% | 2026-05-06 | Fidelity Brokerage Services LLC |
| 2026-05-01 | Bartram RichardFormer Officer | 5K | $159K | 0.011% | 2026-05-01 | Fidelity Brokerage Services LLC |
| 2026-04-22 | Bartram RichardFormer Officer | 10K | $341K | 0.022% | 2026-04-22 | Fidelity Brokerage Services LLC |
| 2026-03-25 | Bartram RichardFormer Officer | 1K | $30K | 0.002% | 2026-03-25 | Fidelity Brokerage Services LLC |
| 2026-03-16 | Bartram RichardFormer Officer | 10K | $300K | 0.021% | 2026-03-16 | Fidelity Brokerage Services LLC |
| 2026-01-12 | CORNELIUS JAMES MFormer Director | 31K | $1.1M | 0.069% | 2026-01-12 | Fidelity Brokerage Services LLC |
Large holders (13D and 13G)
One row per reporting person with its latest filing, newest first, 50 of 51 shown. JSON29 holders report 5% or more of MBX in their latest filing, 19 on Schedule 13D (active intent). The largest reported stake is Patrick J. Heron at 11.7% of the class (5,243,421 shares), filed 2026-08-10 for an event on 2026-08-06.
| Filed | Form | Holder | Shares | Of class | Event |
|---|---|---|---|---|---|
| 2026-08-14 | 13G/Ano. 2 | David Kroinparent holding company, individual | 1.7M | 3.6% | 2026-06-30 |
| 2026-08-14 | 13G/Ano. 2 | Deep Track Capital, LPinvestment adviser, other entity | 1.7M | 3.6% | 2026-06-30 |
| 2026-08-14 | 13G/Ano. 2 | Deep Track Biotechnology Master Fund, Ltd.corporation | 1.7M | 3.6% | 2026-06-30 |
| 2026-08-10 | 13D/Ano. 3 | Patrick J. Heronindividual | 5.2M | 11.7% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | James N. Topperindividual | 5.2M | 11.7% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | FHMLS X, L.L.C.other entity | 5.2M | 10.8% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | Frazier Life Sciences X, L.P.partnership | 5.2M | 10.8% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | FHMLS X, L.P.partnership | 5.2M | 10.8% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | FHMLSP, L.L.C.other entity | 1.4M | 3.0% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | Frazier Life Sciences Public Fund, L.P.partnership | 1.4M | 3.0% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | FHMLSP, L.P.partnership | 1.4M | 3.0% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | FHMLS XI, L.L.C.other entity | 3K | 0.0% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | Frazier Life Sciences XI, L.P.partnership | 3K | 0.0% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | FHMLS XI, L.P.partnership | 3K | 0.0% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | ORBIMED ADVISORS LLCinvestment adviser | 3.1M | 6.4% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | ORBIMED CAPITAL GP VII LLCother entity | 2.5M | 5.2% | 2026-08-06 |
| 2026-08-10 | 13D/Ano. 3 | ORBIMED GENESIS GP LLCother entity | 570K | 1.2% | 2026-08-06 |
| 2026-07-29 | 13G | BlackRock, Inc.parent holding company | 2.6M | 5.5% | 2026-06-30 |
| 2026-07-08 | 13G/Ano. 5 | Wellington Investment Advisors Holdings LLPparent holding company | 5.0M | 10.5% | 2026-06-30 |
| 2026-07-08 | 13G/Ano. 5 | Wellington Group Holdings LLPparent holding company | 5.0M | 10.5% | 2026-06-30 |
| 2026-07-08 | 13G/Ano. 5 | Wellington Management Group LLPparent holding company | 5.0M | 10.5% | 2026-06-30 |
| 2026-07-08 | 13G/Ano. 5 | Wellington Management Company LLPinvestment adviser | 5.0M | 9.8% | 2026-06-30 |
| 2026-07-08 | 13G/Ano. 1 | FMR LLCparent holding company | 5.3M | 11.2% | 2026-06-30 |
| 2026-07-08 | 13G/Ano. 1 | Abigail P. Johnsonindividual | 5.3M | 11.2% | 2026-06-30 |
| 2026-06-24 | 13G | Senai Asefaw, M.D.individual | 2.5M | 5.2% | 2026-06-16 |
| 2026-06-24 | 13G | Paradigm BioCapital Advisors GP LLCother entity | 2.5M | 5.2% | 2026-06-16 |
| 2026-06-24 | 13G | Paradigm BioCapital Advisors LPpartnership | 2.5M | 5.2% | 2026-06-16 |
| 2026-06-24 | 13G | Paradigm BioCapital International Fund Ltd.corporation | 2.2M | 4.6% | 2026-06-16 |
| 2025-11-14 | 13G/Ano. 1 | P. Kent Hawrylukindividual | 2.0M | 4.3% | 2025-09-30 |
| 2025-11-12 | 13G/Ano. 1 | Wellington Biomedical Innovation Master Investors (Cayman) II, L.P.partnership | 2.0M | 4.5% | 2025-09-30 |
| 2025-11-10 | 13D/Ano. 1 | Rick Yangindividual | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | Mohamad H. Makhzoumiindividual | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | Edward T. Mathersindividual | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | Scott D. Sandellindividual | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | Paul Walkerindividual | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | New Enterprise Associates 17, L.P.partnership | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | NEA Partners 17, L.P.partnership | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | NEA 17 GP, LLCother entity | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | Forest Baskettindividual | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | Ali Behbahaniindividual | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | Carmen Changindividual | 3.6M | 8.1% | 2025-11-06 |
| 2025-11-10 | 13D/Ano. 1 | Anthony A. Florence, Jr.individual | 3.6M | 8.1% | 2025-11-06 |
| 2025-09-30 | 13D/Ano. 1 | Norwest Venture Partners XVI, LPpartnership | 2.1M | 4.8% | 2025-09-26 |
| 2025-09-30 | 13D/Ano. 1 | NVP Associates, LLCother entity | 2.1M | 4.8% | 2025-09-26 |
| 2025-09-30 | 13D/Ano. 1 | Genesis VC Partners XVI, LLCother entity | 2.1M | 4.8% | 2025-09-26 |
| 2025-09-30 | 13D/Ano. 1 | Tiba Aynechiindividual | 2.1M | 4.8% | 2025-09-26 |
| 2025-09-30 | 13D/Ano. 1 | Jon Erik Kossowindividual | 2.1M | 4.8% | 2025-09-26 |
| 2025-09-30 | 13D/Ano. 1 | Jeffrey Croweindividual | 2.1M | 4.8% | 2025-09-26 |
| 2025-09-30 | 13D/Ano. 2 | FHMLSP Overage, L.L.C.other entity | 326K | 0.7% | 2025-09-26 |
| 2025-09-30 | 13D/Ano. 2 | FHMLSP Overage, L.P.partnership | 326K | 0.7% | 2025-09-26 |
13F holders
Tracked managers holding MBX at their latest 13F. JSON4 of the 30 tracked managers held MBX at their latest 13F, $30.1M in total at quarter-end prices. Millennium Management is the largest at $12.5M (0.0% of its portfolio) as of 2026-06-30. Over the prior quarter 0 added shares and 4 cut.
| Fund | Quarter | Shares | Value | Of portfolio | Change in shares |
|---|---|---|---|---|---|
| Millennium Management | 2026-06-30 | 226K | $12.5M | 0.00% | -338K |
| D. E. Shaw & Co. | 2026-06-30 | 183K | $10.1M | 0.00% | -106K |
| Two Sigma Investments | 2026-06-30 | 113K | $6.3M | 0.00% | -2K |
| AQR Capital Management | 2026-06-30 | 23K | $1.2M | 0.00% | -5K |
Only the 30 tracked managers on the funds hub; a 13F reports long positions in US listed stock at quarter end, 45 days late, and says nothing about shorts or positions sold since.
What this page is
MBX Biosciences in the regulatory record
Regulators publish company data in separate files that never sit next to each other: FINRA's twice-monthly short interest, its daily short sale volume, the SEC's fails-to-deliver counts, and each insider's Form 4. A company page puts those series for one ticker on one URL, with planned sales, large holders, 13F holders and financials beside them, so the short position, the daily flow, the settlement fails and what insiders are doing can be read together.
Each section has its own history table, a one-line summary of the latest figures and its own JSON and CSV links, and says when its source last updated.
This page follows MBX Biosciences (MBX), SEC CIK 1776111, listed on Nasdaq, classified by the SEC as pharmaceutical preparations. The cross-market tables live on the short interest and insider transactions hubs.
Source and updates
- Short interest
- FINRA consolidated short interestSource: FINRA.Twice a month, about eight business days after settlement. Latest 2026-10-15.JSON and CSV
- Daily short volume
- FINRA Reg SHO daily filesSource: FINRA.Every trading day, the morning after FINRA posts it. Latest 2026-11-03.JSON and CSV
- Fails to deliver
- SEC fails-to-deliver dataSource: SEC.Twice a month, a few weeks after the half month ends. Latest 2026-09-04.JSON and CSV
- Planned sales
- SEC EDGAR Form 144Source: SEC.New notices appear shortly after the SEC posts them; a notice is filed on or before the sale. Latest 2026-08-17.JSON and CSV
- Large holders
- SEC EDGAR Schedule 13D and 13GSource: SEC.New filings appear shortly after the SEC posts them. A 13D is due within five business days of crossing 5%; a 13G follows the passive schedule. Latest 2026-08-14.JSON and CSV
- 13F holders
- SEC EDGAR Form 13F-HRSource: SEC.Quarterly, filed within 45 days of quarter end; 30 tracked managers. Latest 2026-06-30.JSON and CSV
- Earnings dates
- SEC EDGAR 8-K filings (Item 2.02)Source: SEC.Twice a day. Reported dates come from the company's 8-K filings; the next date is marked as an estimate until the 8-K arrives. Latest 2026-08-06.JSON and CSV
- Insider trades
- SEC EDGAR Form 4Source: SEC.New filings appear shortly after the SEC posts them; they're due two business days after the trade. Latest 2026-08-04.JSON and CSV
- Company record
- EDGAR filing index for CIK 1776111Ticker, name and exchange from the SEC's company list, refreshed weekly.
- Rate limits
- 10 requests a minute without a key, 30 with a free key from a free account.
How to read it
- Read the position against the flow: rising short interest with a high daily short share is new shorting; rising short interest with a normal short share is old shorts holding on.
- Insider buys next to a large short position are rare and stand out; insider sells next to one are common and mean little.
- Fails to deliver matter relative to the float, not in absolute shares; a million failed shares in a mega cap is noise.
Analysis of what the data shows, not advice. XOOMAR does not recommend buying, selling or holding anything.
Other companies the SEC classifies as pharmaceutical preparations
Other company pages
Datasets
Frequently Asked Questions
How much of MBX is sold short?
4,422,964 shares were held short at the 2026-10-15 settlement, 7.5 days of average volume. FINRA publishes the next count about eight business days after the 15th and the last business day of the month.
What is MBX's daily short volume?
On 2026-11-03, 57,100 of the 89,759 MBX shares reported to FINRA were sold short, 63.6% of the day's reported volume. Short volume is a flow for one day, not a position.
Does MBX have fails to deliver?
The SEC's latest file shows 100 MBX shares failed to deliver at settlement 2026-09-04. Fails are reported per settlement date and published twice a month with a lag.
Are MBX insiders buying or selling?
No open-market insider trades were reported for MBX in the last 90 days. The most recent filings are listed below. Latest filing: Azoulay Salomon (Chief Medical Officer) on 2026-08-04.
Have MBX insiders filed to sell?
17 Form 144 notices on file for MBX worth $7.8M at the prices reported; 1 in the last 90 days worth $256K. Latest: Hawryluk P. Kent filed on 2026-08-17 to sell 3,745 shares ($256K) from 2026-08-17.
Who owns 5% or more of MBX?
29 holders report 5% or more of MBX in their latest filing, 19 on Schedule 13D (active intent). The largest reported stake is Patrick J. Heron at 11.7% of the class (5,243,421 shares), filed 2026-08-10 for an event on 2026-08-06.
Which tracked 13F managers own MBX?
4 of the 30 tracked 13F managers held MBX shares at their latest filing, $30.1M in all. The largest: Izzy Englander's Millennium Management (226K shares, $12.5M), D. E. Shaw & Co. (183K shares, $10.1M), Two Sigma Investments (113K shares, $6.3M), Cliff Asness's AQR Capital Management (23K shares, $1.2M).
Data on this page is provided for informational purposes only and is not financial advice. See our editorial policy.