Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
320 institutional managers reported holding MTRN for the quarter ended Mar 31, 2026. Together they hold about 93% of shares outstanding; the top 10 hold 56%. 59 opened new positions; 31 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| BlackRock | 3.37M | 16.04% | $487.5M | added +2.1% | ≤2013 |
| Vanguard Group | 2.45M | 11.65% | $354.1M | added +4.3% | ≤2013 |
| State Street | 1.33M | 6.32% | $192.2M | added +9.8% | ≤2013 |
| Dimensional Fund Advisors | 885.2k | 4.21% | $128.1M | trimmed -10.7% | ≤2013 |
| American Century Companies INC | 882.7k | 4.20% | $127.7M | added +69.3% | 2023 Q1 |
| Capital Research Global Investors | 789.9k | 3.76% | $114.3M | trimmed -58.3% | 2022 Q3 |
| Barrow Hanley Mewhinney & Strauss LLC | 529.8k | 2.52% | $76.7M | trimmed -6% | 2020 Q2 |
| Geode Capital | 504.0k | 2.40% | $72.9M | added +2.9% | ≤2013 |
| ACK Asset Management LLC (focused) | 474.8k | 2.26% | $68.7M | unchanged | 2020 Q1 |
| Fisher Investments | 442.0k | 2.10% | $64.0M | added +215.1% | 2018 Q4 |
| Morgan Stanley | 424.5k | 2.02% | $61.4M | trimmed -1.2% | ≤2013 |
| Capital Group (American Funds) | 415.0k | 1.98% | $60.0M | opened | 2026 Q1 |
| Trigran Investments, INC. (focused) | 334.0k | 1.59% | $48.3M | trimmed -27.1% | 2022 Q2 |
| Harvey Partners, LLC (focused) | 293.1k | 1.40% | $42.4M | trimmed -8.3% | 2025 Q3 |
| Raymond James Financial INC | 292.6k | 1.39% | $42.3M | added +1.6% | 2024 Q4 |
| Charles Schwab Investment Management | 292.5k | 1.39% | $42.3M | trimmed -3.7% | ≤2013 |
| Copeland Capital Management, LLC | 265.2k | 1.26% | $38.4M | trimmed -13% | 2020 Q3 |
| Mirae Asset Global Etfs Holdings LTD. | 260.5k | 1.24% | $37.7M | trimmed -11.4% | 2023 Q1 |
| Northern Trust | 247.8k | 1.18% | $35.9M | trimmed -0.6% | ≤2013 |
| Royal Bank OF Canada | 219.1k | 1.04% | $31.7M | trimmed -14.9% | ≤2013 |
| Gamco Investors, INC. et al | 191.2k | 0.91% | $27.7M | trimmed -2.4% | ≤2013 |
| Invesco | 179.2k | 0.85% | $25.9M | added +142.7% | ≤2013 |
| Kennedy Capital Management LLC | 166.0k | 0.79% | $24.0M | added +0.8% | 2017 Q4 |
| Aberdeen Group plc | 164.4k | 0.78% | $23.8M | trimmed -16.3% | 2021 Q2 |
| BNY Mellon | 152.5k | 0.73% | $22.1M | trimmed -2.9% | ≤2013 |
| Granahan Investment Management, LLC | 144.5k | 0.69% | $20.9M | added +4.5% | 2019 Q1 |
| Nuveen | 143.2k | 0.68% | $20.7M | added +107.9% | 2019 Q2 |
| Schroder Investment Management Group | 131.7k | 0.63% | $19.1M | trimmed -3% | 2022 Q2 |
| Principal Financial Group INC | 120.2k | 0.57% | $17.4M | added +21.5% | ≤2013 |
| Bank OF America CORP /DE/ | 118.6k | 0.56% | $17.2M | added +8.7% | ≤2013 |
| Goldman Sachs | 116.8k | 0.56% | $16.9M | added +56.5% | ≤2013 |
| Royce & Associates | 103.5k | 0.49% | $15.0M | trimmed -4.5% | 2025 Q3 |
| First Eagle Investment Management | 102.0k | 0.48% | $14.8M | added +75.8% | 2025 Q3 |
| UBS | 97.8k | 0.47% | $14.2M | trimmed -4.7% | ≤2013 |
| Ceredex Value Advisors LLC | 97.5k | 0.46% | $14.1M | opened | 2024 Q2 |
| Panagora Asset Management INC | 85.2k | 0.41% | $12.3M | added +89.5% | 2025 Q3 |
| Ameriprise Financial INC | 80.4k | 0.38% | $11.6M | trimmed -3.7% | ≤2013 |
| SEI Investments CO | 79.6k | 0.38% | $11.5M | added +12.8% | 2021 Q2 |
| King Luther Capital Management CORP | 78.1k | 0.37% | $11.3M | added +5.5% | 2024 Q2 |
| Public Sector Pension Investment Board | 74.2k | 0.35% | $10.7M | added +3.5% | ≤2013 |
| Gendell Jeffrey L | 71.3k | 0.34% | $10.3M | unchanged | 2025 Q2 |
| Qube Research & Technologies LTD | 65.5k | 0.31% | $9.5M | opened | 2026 Q1 |
| HighTower Advisors, LLC | 65.3k | 0.31% | $9.4M | added +3% | 2023 Q3 |
| Rhumbline Advisers | 64.2k | 0.31% | $9.3M | added +1.4% | ≤2013 |
| Envestnet Asset Management INC | 62.6k | 0.30% | $9.1M | trimmed -3.4% | 2019 Q2 |
| Fiera Capital CORP | 58.6k | 0.28% | $8.5M | added +28.2% | 2017 Q4 |
| Wells Fargo & COMPANY/MN | 57.3k | 0.27% | $8.3M | trimmed -21% | ≤2013 |
| Mutual OF America Capital Management LLC | 53.4k | 0.25% | $7.7M | unchanged | 2018 Q2 |
| Legal & General Group PLC | 51.8k | 0.25% | $7.5M | trimmed -1.1% | 2014 Q3 |
| Lumbard & Kellner, LLC | 51.6k | 0.25% | $7.5M | unchanged | 2025 Q2 |
Largest 50 of 320 shown; the full ranked, searchable register is at boothcheck.com/holders/MTRN. 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.