Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
388 institutional managers reported holding MMSI for the quarter ended Mar 31, 2026. Reported positions total over 95% of shares outstanding; the top 10 hold 48%. 64 opened new positions; 58 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| BlackRock | 8.83M | 14.72% | $608.6M | added +1.5% | ≤2013 |
| Vanguard Group | 6.69M | 11.15% | $460.8M | added +1.6% | ≤2013 |
| State Street | 2.36M | 3.93% | $162.7M | added +5.8% | ≤2013 |
| Conestoga Capital Advisors, LLC | 2.17M | 3.61% | $149.3M | added +3.9% | 2019 Q2 |
| Fuller & Thaler Asset Management, INC. | 2.12M | 3.52% | $145.7M | added +1.8% | 2020 Q1 |
| Nomura Asset Management International INC. | 1.62M | 2.71% | $111.9M | added +4% | 2023 Q4 |
| Geode Capital | 1.51M | 2.51% | $103.9M | added +3.8% | ≤2013 |
| Morgan Stanley | 1.26M | 2.10% | $86.9M | added +10.6% | ≤2013 |
| Dimensional Fund Advisors | 1.24M | 2.06% | $85.2M | added +1% | ≤2013 |
| Greenhouse Funds Lllp (focused) | 1.12M | 1.87% | $77.3M | added +29.4% | 2023 Q1 |
| Citigroup INC | 1.06M | 1.77% | $73.2M | unchanged | ≤2013 |
| Congress Asset Management CO | 1.03M | 1.72% | $70.9M | added +20% | 2023 Q4 |
| FMR (Fidelity) | 1.00M | 1.68% | $69.2M | trimmed -43.3% | ≤2013 |
| Citadel Advisors | 962.8k | 1.60% | $66.3M | trimmed -12% | 2020 Q4 |
| Westwood Holdings Group INC | 946.5k | 1.58% | $65.2M | added +14.6% | 2019 Q4 |
| Royal Bank OF Canada | 921.3k | 1.53% | $63.5M | trimmed -4.7% | ≤2013 |
| William Blair Investment Management, LLC | 777.5k | 1.30% | $53.6M | trimmed -11.1% | 2019 Q4 |
| Point72 | 741.9k | 1.24% | $51.1M | added +70% | 2025 Q3 |
| Maverick Capital | 714.1k | 1.19% | $49.2M | added +46.9% | 2025 Q1 |
| Northern Trust | 681.8k | 1.14% | $47.0M | unchanged | ≤2013 |
| Charles Schwab Investment Management | 675.4k | 1.13% | $46.5M | unchanged | ≤2013 |
| T. Rowe Price | 655.0k | 1.09% | $45.1M | added +1.6% | ≤2013 |
| Goldman Sachs | 647.8k | 1.08% | $44.6M | trimmed -31.7% | ≤2013 |
| Bank OF America CORP /DE/ | 580.9k | 0.97% | $40.0M | trimmed -20.8% | ≤2013 |
| Marshall Wace | 574.4k | 0.96% | $39.6M | added +292.1% | 2025 Q3 |
| Nuveen | 546.1k | 0.91% | $37.6M | added +13.3% | 2016 Q3 |
| UBS | 496.2k | 0.83% | $34.2M | trimmed -9.4% | ≤2013 |
| Wells Fargo & COMPANY/MN | 491.2k | 0.82% | $33.8M | trimmed -7.2% | ≤2013 |
| Manufacturers Life Insurance Company, THE | 448.3k | 0.75% | $30.9M | added +49.6% | ≤2013 |
| MFS Investment Management | 447.5k | 0.75% | $30.8M | opened | 2026 Q1 |
| Frontier Capital Management CO LLC | 430.6k | 0.72% | $29.7M | added +97.9% | ≤2013 |
| Aberdeen Group plc | 428.3k | 0.71% | $29.5M | trimmed -9.6% | 2023 Q3 |
| Oberweis Asset Management INC/ | 424.2k | 0.71% | $29.2M | added +57.8% | 2020 Q2 |
| Fort Washington Investment Advisors INC /OH/ | 420.9k | 0.70% | $29.0M | added +31.1% | 2022 Q3 |
| BNY Mellon | 383.8k | 0.64% | $26.4M | trimmed -4.5% | ≤2013 |
| Freestone Grove Partners LP | 382.9k | 0.64% | $26.4M | added +488.7% | 2025 Q3 |
| Aristotle Capital Boston, LLC | 377.6k | 0.63% | $26.0M | unchanged | 2014 Q4 |
| Raymond James Financial INC | 376.8k | 0.63% | $26.0M | trimmed -14.7% | ≤2013 |
| Principal Financial Group INC | 350.2k | 0.58% | $24.1M | added +4.5% | ≤2013 |
| ArrowMark Colorado Holdings LLC | 348.6k | 0.58% | $24.0M | trimmed -23.8% | 2013 Q4 |
| Balyasny Asset Management | 320.7k | 0.53% | $22.1M | added +140.3% | 2025 Q2 |
| Renaissance Technologies | 314.2k | 0.52% | $21.6M | added +149% | 2023 Q1 |
| Fifth Third Bancorp | 313.0k | 0.52% | $21.6M | added +24625.6% | 2018 Q1 |
| Wellington Management | 303.8k | 0.51% | $20.9M | trimmed -77.1% | 2024 Q4 |
| Champlain Investment Partners, LLC | 290.5k | 0.48% | $20.0M | trimmed -20.9% | 2025 Q4 |
| Boston Trust Walden CORP | 277.2k | 0.46% | $19.1M | opened | 2026 Q1 |
| Envestnet Asset Management INC | 264.7k | 0.44% | $18.2M | added +6.8% | 2017 Q1 |
| Franklin Resources | 259.7k | 0.43% | $17.9M | trimmed -37.8% | 2020 Q4 |
| Silvercrest Asset Management Group LLC | 259.7k | 0.43% | $17.9M | added +27.3% | 2025 Q4 |
| Ameriprise Financial INC | 250.9k | 0.42% | $17.3M | trimmed -16.6% | ≤2013 |
Largest 50 of 388 shown; the full ranked, searchable register is at boothcheck.com/holders/MMSI. 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.