Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
497 institutional managers reported holding MTSI for the quarter ended Mar 31, 2026. Together they hold about 93% of shares outstanding; the top 10 hold 54%. 97 opened new positions; 50 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| FMR (Fidelity) | 10.61M | 13.68% | $2.36B | added +63.7% | ≤2013 |
| BlackRock | 8.57M | 11.04% | $1.90B | added +13.8% | ≤2013 |
| Vanguard Group | 7.09M | 9.15% | $1.57B | trimmed -2% | ≤2013 |
| T. Rowe Price Investment Management, INC. | 4.49M | 5.78% | $995.9M | added +58.2% | 2023 Q1 |
| Invesco | 3.67M | 4.74% | $815.6M | added +7.3% | 2014 Q4 |
| State Street | 2.15M | 2.78% | $477.9M | added +1.6% | ≤2013 |
| Wellington Management | 1.55M | 2.00% | $343.6M | added +52.4% | 2024 Q4 |
| Geode Capital | 1.36M | 1.75% | $301.8M | added +7.3% | ≤2013 |
| Capital Research Global Investors | 1.22M | 1.58% | $271.4M | trimmed -8.5% | 2017 Q2 |
| Whale Rock Capital (focused) | 1.17M | 1.51% | $260.8M | added +50% | 2025 Q4 |
| Artisan Partners | 1.05M | 1.35% | $232.5M | trimmed -16% | 2022 Q3 |
| UBS | 1.00M | 1.29% | $222.0M | trimmed -6.9% | 2013 Q3 |
| Polar Capital Holdings PLC | 930.8k | 1.20% | $206.6M | opened | 2026 Q1 |
| T. Rowe Price | 914.9k | 1.18% | $203.1M | trimmed -52.7% | ≤2013 |
| Gw&k Investment Management, LLC | 839.1k | 1.08% | $186.3M | trimmed -31.1% | 2016 Q1 |
| MFS Investment Management | 828.4k | 1.07% | $183.9M | added +77.1% | 2024 Q4 |
| AllianceBernstein | 789.0k | 1.02% | $175.2M | trimmed -25.8% | ≤2013 |
| Neuberger Berman Group LLC | 788.8k | 1.02% | $175.1M | added +18.5% | 2015 Q1 |
| Janus Henderson | 784.1k | 1.01% | $174.1M | added +15.5% | 2021 Q3 |
| Barclays PLC | 734.6k | 0.95% | $163.1M | added +27.9% | ≤2013 |
| Charles Schwab Investment Management | 660.9k | 0.85% | $146.7M | added +3% | ≤2013 |
| Nomura Asset Management International INC. | 642.1k | 0.83% | $142.5M | trimmed -16.7% | 2020 Q3 |
| Citadel Advisors | 590.6k | 0.76% | $131.1M | added +343.6% | 2017 Q3 |
| Raymond James Financial INC | 590.3k | 0.76% | $131.0M | trimmed -2% | 2020 Q4 |
| Morgan Stanley | 555.2k | 0.72% | $123.2M | trimmed -26.8% | ≤2013 |
| Bessemer Group INC | 533.3k | 0.69% | $118.4M | trimmed -6.3% | 2023 Q1 |
| Northern Trust | 532.7k | 0.69% | $118.3M | added +4.5% | ≤2013 |
| Dimensional Fund Advisors | 529.1k | 0.68% | $117.5M | trimmed -44.1% | 2013 Q3 |
| Stephens Investment Management Group LLC | 515.8k | 0.67% | $114.5M | trimmed -4.7% | 2024 Q1 |
| Franklin Resources | 502.0k | 0.65% | $111.4M | added +3161% | 2022 Q3 |
| Bank OF America CORP /DE/ | 480.7k | 0.62% | $106.7M | trimmed -26.8% | ≤2013 |
| Rafferty Asset Management, LLC | 467.6k | 0.60% | $103.8M | trimmed -19.4% | 2025 Q3 |
| Analog Century Management LP (focused) | 436.3k | 0.56% | $96.9M | trimmed -28% | 2020 Q4 |
| Goldman Sachs | 430.8k | 0.56% | $95.6M | trimmed -18.8% | 2015 Q1 |
| Citigroup INC | 423.9k | 0.55% | $94.1M | added +45.3% | ≤2013 |
| BNY Mellon | 400.9k | 0.52% | $89.0M | added +4.2% | ≤2013 |
| Geneva Capital Management LLC | 343.8k | 0.44% | $76.3M | trimmed -7.7% | 2025 Q2 |
| American Century Companies INC | 343.3k | 0.44% | $76.2M | trimmed -33.1% | 2020 Q4 |
| TimesSquare Capital Management, LLC | 341.2k | 0.44% | $75.7M | added +38.2% | 2021 Q2 |
| Driehaus Capital Management LLC | 336.8k | 0.43% | $74.8M | trimmed -30.1% | 2025 Q2 |
| Millennium Management | 335.2k | 0.43% | $74.4M | trimmed -44.4% | 2018 Q2 |
| Loomis Sayles & CO L P | 322.5k | 0.42% | $71.6M | trimmed -33.4% | 2020 Q1 |
| Manufacturers Life Insurance Company, THE | 306.0k | 0.39% | $67.9M | trimmed -36.6% | ≤2013 |
| Jennison Associates LLC | 299.7k | 0.39% | $66.5M | trimmed -15% | 2020 Q4 |
| Lord, Abbett & CO. LLC | 253.4k | 0.33% | $56.3M | added +12.1% | 2023 Q3 |
| Schroder Investment Management Group | 250.0k | 0.32% | $55.5M | trimmed -23.7% | 2019 Q2 |
| NEW York State Common Retirement Fund | 242.9k | 0.31% | $53.9M | trimmed -16.6% | 2015 Q2 |
| First Trust Advisors LP | 228.4k | 0.29% | $50.7M | added +221% | 2022 Q4 |
| Fiera Capital CORP | 224.7k | 0.29% | $49.9M | trimmed -40.6% | 2025 Q2 |
| TD Asset Management INC | 221.4k | 0.28% | $49.1M | trimmed -20.9% | 2023 Q1 |
Largest 50 of 497 shown; the full ranked, searchable register is at boothcheck.com/holders/MTSI. 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.