Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
433 institutional managers reported holding MKTX for the quarter ended Mar 31, 2026. Reported positions total over 95% of shares outstanding; the top 10 hold 63%. 53 opened new positions; 98 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| BlackRock | 4.08M | 11.52% | $672.6M | added +8.8% | ≤2013 |
| Vanguard Group | 4.06M | 11.48% | $670.7M | added +5.7% | ≤2013 |
| PRIMECAP Management | 3.35M | 9.46% | $552.4M | added +5.4% | ≤2013 |
| AQR Capital | 2.68M | 7.58% | $443.0M | added +4.9% | ≤2013 |
| North Reef Capital Management LP | 1.88M | 5.30% | $309.5M | added +16.5% | 2023 Q3 |
| FMR (Fidelity) | 1.52M | 4.29% | $250.8M | trimmed -24.2% | 2016 Q1 |
| State Street | 1.28M | 3.62% | $211.4M | added +2.6% | ≤2013 |
| VAN ECK Associates CORP | 1.24M | 3.50% | $204.5M | added +2% | 2019 Q4 |
| Millennium Management | 1.09M | 3.07% | $179.4M | added +260.4% | 2018 Q4 |
| Bank OF Montreal /CAN/ | 1.02M | 2.88% | $168.4M | added +7.3% | ≤2013 |
| Neuberger Berman Group LLC | 966.0k | 2.73% | $159.4M | added +75.8% | 2014 Q2 |
| Geode Capital | 863.0k | 2.44% | $142.4M | added +3.6% | ≤2013 |
| Guardcap Asset Management LTD (focused) | 643.4k | 1.82% | $106.2M | trimmed -44.2% | 2018 Q4 |
| Dimensional Fund Advisors | 581.5k | 1.64% | $96.0M | added +10.3% | ≤2013 |
| Two Sigma | 524.0k | 1.48% | $86.5M | trimmed -1.8% | 2022 Q1 |
| BNP Paribas Financial Markets | 522.7k | 1.48% | $86.3M | trimmed -7.7% | ≤2013 |
| Goldman Sachs | 509.0k | 1.44% | $84.0M | added +194.9% | ≤2013 |
| Morgan Stanley | 490.5k | 1.39% | $81.0M | added +15.5% | ≤2013 |
| Findlay Park Partners LLP | 480.6k | 1.36% | $79.3M | trimmed -10.4% | 2024 Q3 |
| UBS | 379.3k | 1.07% | $62.6M | added +80.3% | ≤2013 |
| Walleye Capital LLC | 351.8k | 0.99% | $58.1M | added +108.5% | 2021 Q2 |
| Charles Schwab Investment Management | 338.5k | 0.96% | $55.9M | added +6.3% | ≤2013 |
| Arrowstreet Capital | 295.5k | 0.83% | $48.8M | added +2.3% | 2024 Q3 |
| Rdst Capital LLC (focused) | 295.3k | 0.83% | $48.7M | trimmed -5% | 2025 Q1 |
| BNY Mellon | 289.9k | 0.82% | $47.9M | trimmed -2.9% | ≤2013 |
| Bank OF America CORP /DE/ | 263.9k | 0.75% | $43.5M | added +32.4% | ≤2013 |
| Amundi | 258.7k | 0.73% | $42.7M | added +803.9% | 2017 Q4 |
| Point72 | 252.8k | 0.71% | $41.7M | opened | 2021 Q4 |
| Driehaus Capital Management LLC | 239.3k | 0.68% | $39.5M | opened | 2026 Q1 |
| Northern Trust | 236.3k | 0.67% | $39.0M | added +0.9% | ≤2013 |
| Cooke & Bieler LP | 226.2k | 0.64% | $37.3M | added +117.3% | 2025 Q4 |
| Champlain Investment Partners, LLC | 210.1k | 0.59% | $34.7M | added +103.3% | 2025 Q4 |
| Victory Capital Management INC | 204.9k | 0.58% | $33.8M | added +118.8% | 2016 Q1 |
| Public Sector Pension Investment Board | 192.2k | 0.54% | $31.7M | added +49.4% | 2019 Q2 |
| Principal Financial Group INC | 181.8k | 0.51% | $30.0M | added +2.1% | ≤2013 |
| Connor, Clark & Lunn Investment Management LTD. | 174.1k | 0.49% | $28.7M | added +2% | 2024 Q1 |
| IEQ Capital, LLC | 173.9k | 0.49% | $28.7M | trimmed -8.2% | 2024 Q4 |
| Janus Henderson | 168.8k | 0.48% | $27.9M | unchanged | ≤2013 |
| Renaissance Technologies | 167.1k | 0.47% | $27.6M | trimmed -5.1% | ≤2013 |
| Sone Capital Management, LLC | 160.0k | 0.45% | $26.4M | added +1444.8% | 2024 Q4 |
| Nuveen | 148.1k | 0.42% | $24.4M | added +10.1% | 2019 Q2 |
| Healthcare OF Ontario Pension Plan Trust Fund | 145.6k | 0.41% | $24.0M | added +374.5% | 2025 Q1 |
| HRT Financial LP | 137.0k | 0.39% | $22.6M | trimmed -36% | 2024 Q2 |
| Raymond James Financial INC | 121.6k | 0.34% | $20.1M | added +7.2% | ≤2013 |
| Invesco | 118.3k | 0.33% | $19.5M | added +3.2% | ≤2013 |
| Eubel Brady & Suttman Asset Management INC | 111.5k | 0.32% | $18.4M | opened | 2026 Q1 |
| Davis Asset Management, L.p. | 108.8k | 0.31% | $18.0M | opened | 2026 Q1 |
| Flossbach VON Storch SE | 108.1k | 0.30% | $17.8M | added +16.1% | 2023 Q3 |
| Assenagon Asset Management S.a. | 104.8k | 0.30% | $17.3M | added +65.8% | 2022 Q2 |
| Polar Asset Management Partners INC. | 104.2k | 0.29% | $17.2M | added +523.8% | 2025 Q3 |
Largest 50 of 433 shown; the full ranked, searchable register is at boothcheck.com/holders/MKTX. Related filers are grouped using the filings' own included-manager declarations. Historically, several managers opening new positions in the same quarter said almost nothing about the quarter that followed (59,118 cases since 2013). A filed record, not a forecast. Nothing here is investment advice.