Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
409 institutional managers reported holding MAT for the quarter ended Mar 31, 2026. Reported positions total over 95% of shares outstanding; the top 10 hold 65%. 62 opened new positions; 87 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| EdgePoint Investment Group INC. (focused) | 49.14M | 16.33% | $713.5M | added +3.8% | 2018 Q2 |
| Vanguard Group | 29.79M | 9.90% | $432.6M | trimmed -2.4% | ≤2013 |
| PRIMECAP Management | 29.70M | 9.87% | $431.2M | unchanged | 2017 Q2 |
| BlackRock | 27.32M | 9.08% | $396.7M | added +1.8% | ≤2013 |
| Ariel Investments, LLC | 13.57M | 4.51% | $197.0M | added +8.3% | 2015 Q2 |
| Southeastern Asset Management INC/TN/ (focused) | 12.81M | 4.26% | $186.0M | added +49.5% | 2017 Q3 |
| Dimensional Fund Advisors | 11.05M | 3.67% | $160.5M | added +7.6% | ≤2013 |
| State Street | 9.72M | 3.23% | $141.1M | added +1.1% | ≤2013 |
| LSV Asset Management | 6.24M | 2.07% | $90.6M | added +1.8% | 2024 Q2 |
| Geode Capital | 6.17M | 2.05% | $89.6M | added +3.1% | ≤2013 |
| T. Rowe Price | 6.09M | 2.02% | $88.5M | trimmed -6.7% | ≤2013 |
| AQR Capital | 4.62M | 1.53% | $67.1M | added +12.6% | 2020 Q2 |
| Alyeska Investment Group | 4.61M | 1.53% | $66.9M | added +33.8% | 2025 Q2 |
| D. E. Shaw | 3.88M | 1.29% | $56.4M | added +63.8% | 2019 Q1 |
| Marshall Wace | 3.73M | 1.24% | $54.1M | added +27311.4% | 2025 Q2 |
| Morgan Stanley | 3.55M | 1.18% | $51.5M | trimmed -33.7% | ≤2013 |
| Goldman Sachs | 3.54M | 1.18% | $51.5M | added +37.8% | ≤2013 |
| Charles Schwab Investment Management | 3.37M | 1.12% | $49.0M | added +3.6% | ≤2013 |
| UBS | 3.02M | 1.00% | $43.8M | added +27.8% | ≤2013 |
| Millennium Management | 2.80M | 0.93% | $40.7M | added +25.4% | 2014 Q3 |
| Northern Trust | 2.79M | 0.93% | $40.6M | added +1.8% | ≤2013 |
| Victory Capital Management INC | 2.59M | 0.86% | $37.6M | added +34.7% | 2015 Q4 |
| Squarepoint Ops LLC | 2.37M | 0.79% | $34.4M | trimmed -35.3% | 2020 Q1 |
| Point72 | 2.22M | 0.74% | $32.3M | trimmed -48.8% | 2020 Q2 |
| SEI Investments CO | 2.16M | 0.72% | $31.4M | added +107.3% | ≤2013 |
| Serenity Capital Management Pte. LTD. (focused) | 2.00M | 0.67% | $29.1M | trimmed -16.1% | 2025 Q4 |
| BNY Mellon | 1.95M | 0.65% | $28.3M | trimmed -3.5% | ≤2013 |
| Long Focus Capital Management, LLC | 1.92M | 0.64% | $27.9M | opened | 2026 Q1 |
| Bank OF America CORP /DE/ | 1.91M | 0.64% | $27.8M | added +14.6% | ≤2013 |
| Frontier Capital Management CO LLC | 1.69M | 0.56% | $24.6M | trimmed -59.9% | 2019 Q4 |
| Fuller & Thaler Asset Management, INC. | 1.65M | 0.55% | $23.9M | trimmed -48.5% | 2024 Q4 |
| HBK Investments L P | 1.30M | 0.43% | $18.9M | opened | 2026 Q1 |
| King Luther Capital Management CORP | 1.24M | 0.41% | $18.0M | added +27.8% | 2025 Q1 |
| Quantinno Capital Management LP | 1.22M | 0.41% | $17.8M | unchanged | 2024 Q1 |
| Interval Partners, LP | 1.19M | 0.40% | $17.3M | opened | 2026 Q1 |
| Qube Research & Technologies LTD | 1.16M | 0.39% | $16.8M | trimmed -11.4% | 2023 Q4 |
| Edmond DE Rothschild Holding S.a. | 960.0k | 0.32% | $13.9M | added +500% | 2018 Q1 |
| Invesco | 913.3k | 0.30% | $13.3M | added +4.3% | ≤2013 |
| Rhumbline Advisers | 805.2k | 0.27% | $11.7M | trimmed -0.6% | ≤2013 |
| Gotham Asset Management | 802.4k | 0.27% | $11.7M | added +1159.9% | 2019 Q1 |
| CastleKnight Management LP | 715.4k | 0.24% | $10.4M | added +106.5% | 2025 Q2 |
| Principal Financial Group INC | 694.0k | 0.23% | $10.1M | added +3.8% | ≤2013 |
| Arrowstreet Capital | 644.3k | 0.21% | $9.4M | added +514.2% | 2023 Q4 |
| Thompson Siegel & Walmsley LLC | 621.5k | 0.21% | $9.0M | added +116% | 2024 Q3 |
| Tudor Investment | 621.1k | 0.21% | $9.0M | added +172.9% | 2025 Q3 |
| Swiss National Bank | 615.3k | 0.20% | $8.9M | trimmed -3.1% | ≤2013 |
| CalPERS | 593.2k | 0.20% | $8.6M | unchanged | ≤2013 |
| American Century Companies INC | 590.5k | 0.20% | $8.6M | trimmed -46.8% | 2014 Q4 |
| Nuveen | 588.0k | 0.20% | $8.5M | added +5.1% | 2019 Q2 |
| Galvin, Gaustad & Stein, LLC | 558.4k | 0.19% | $8.1M | trimmed -55.8% | 2025 Q1 |
Largest 50 of 409 shown; the full ranked, searchable register is at boothcheck.com/holders/MAT. 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.