Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
322 institutional managers reported holding WLK for the quarter ended Mar 31, 2026. Together they hold about 34% of shares outstanding; the top 10 hold 21%. 84 opened new positions; 57 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| Orbis Allan Gray LTD | 5.29M | 4.14% | $618.1M | added +20.7% | 2025 Q3 |
| Capital Group (American Funds) | 4.21M | 3.29% | $491.7M | added +93.9% | 2025 Q4 |
| Vanguard Group | 3.50M | 2.73% | $408.4M | trimmed -10.9% | ≤2013 |
| BlackRock | 3.08M | 2.41% | $359.5M | trimmed -5.6% | ≤2013 |
| T. Rowe Price | 2.41M | 1.88% | $281.1M | added +9% | ≤2013 |
| Brandes Investment Partners, LP | 1.84M | 1.44% | $215.1M | added +10.3% | 2025 Q1 |
| Wellington Management | 1.79M | 1.40% | $209.4M | trimmed -57.5% | 2015 Q1 |
| UBS | 1.79M | 1.40% | $209.3M | added +14% | ≤2013 |
| Dimensional Fund Advisors | 1.47M | 1.15% | $171.2M | trimmed -22.3% | ≤2013 |
| Goldman Sachs | 1.39M | 1.09% | $162.7M | added +84.8% | ≤2013 |
| State Street | 1.38M | 1.08% | $161.2M | trimmed -1.2% | ≤2013 |
| FMR (Fidelity) | 1.31M | 1.02% | $153.2M | added +473.5% | 2016 Q2 |
| Mirae Asset Global Etfs Holdings LTD. | 944.0k | 0.74% | $110.2M | added +7.7% | 2018 Q3 |
| Holocene Advisors | 730.0k | 0.57% | $85.2M | trimmed -40.2% | 2024 Q3 |
| Citadel Advisors | 715.6k | 0.56% | $83.6M | added +252% | ≤2013 |
| Geode Capital | 614.3k | 0.48% | $71.7M | added +3.3% | ≤2013 |
| Nuveen | 564.7k | 0.44% | $65.9M | trimmed -13.5% | 2018 Q1 |
| Morgan Stanley | 486.5k | 0.38% | $56.8M | trimmed -36% | ≤2013 |
| Erste Asset Management GmbH | 395.0k | 0.31% | $46.1M | trimmed -6% | 2019 Q4 |
| Schroder Investment Management Group | 374.5k | 0.29% | $43.7M | opened | 2024 Q3 |
| Balyasny Asset Management | 369.7k | 0.29% | $43.2M | opened | 2024 Q1 |
| Jacobs Levy Equity Management, INC | 349.0k | 0.27% | $40.8M | trimmed -47.8% | 2024 Q2 |
| Woodline Partners LP | 337.1k | 0.26% | $39.4M | trimmed -46.3% | 2025 Q2 |
| Charles Schwab Investment Management | 311.8k | 0.24% | $36.4M | added +4.9% | ≤2013 |
| NEW York State Common Retirement Fund | 309.6k | 0.24% | $36.2M | unchanged | ≤2013 |
| ProShare Advisors LLC | 295.8k | 0.23% | $34.5M | trimmed -32% | 2022 Q4 |
| Allspring Global Investments Holdings, LLC | 285.4k | 0.22% | $33.3M | trimmed -43.7% | 2021 Q4 |
| Janus Henderson | 269.8k | 0.21% | $31.5M | trimmed -19.4% | 2017 Q2 |
| Northern Trust | 269.1k | 0.21% | $31.4M | unchanged | ≤2013 |
| Federated Hermes, INC. | 266.7k | 0.21% | $31.1M | added +147.5% | 2021 Q2 |
| AQR Capital | 260.1k | 0.20% | $30.4M | added +1166.5% | ≤2013 |
| VAN Lanschot Kempen Investment Management N.v. | 244.3k | 0.19% | $28.5M | added +3.6% | 2025 Q2 |
| Bank OF America CORP /DE/ | 237.0k | 0.18% | $27.7M | added +28.5% | ≤2013 |
| D. E. Shaw | 233.2k | 0.18% | $27.2M | trimmed -52% | 2022 Q3 |
| Merewether Investment Management, LP | 219.9k | 0.17% | $25.7M | trimmed -43.3% | 2025 Q3 |
| Deprince Race & Zollo INC | 203.4k | 0.16% | $23.7M | unchanged | 2024 Q4 |
| BNY Mellon | 181.1k | 0.14% | $21.1M | added +3.9% | ≤2013 |
| Invesco | 179.4k | 0.14% | $20.9M | trimmed -15.8% | ≤2013 |
| Teachers Retirement System OF THE State OF Kentucky | 178.2k | 0.14% | $20.8M | added +7.8% | 2022 Q4 |
| Ceredex Value Advisors LLC | 177.9k | 0.14% | $20.8M | trimmed -24.5% | 2025 Q4 |
| Man Group | 160.3k | 0.13% | $18.7M | opened | 2026 Q1 |
| Robotti Robert | 145.0k | 0.11% | $16.9M | trimmed -43.4% | 2015 Q4 |
| Capstone Investment Advisors, LLC | 135.8k | 0.11% | $15.9M | added +4254.2% | 2025 Q4 |
| Sprott INC. | 132.6k | 0.10% | $15.5M | trimmed -5.3% | 2016 Q3 |
| Quantinno Capital Management LP | 121.4k | 0.10% | $14.2M | added +4.4% | 2019 Q4 |
| Recurrent Investment Advisors LLC | 112.8k | 0.09% | $13.2M | added +49.1% | 2019 Q4 |
| Yaupon Capital Management LP | 107.0k | 0.08% | $12.5M | opened | 2026 Q1 |
| Wells Fargo & COMPANY/MN | 106.7k | 0.08% | $12.5M | added +16.1% | ≤2013 |
| Jane Street | 105.7k | 0.08% | $12.3M | opened | 2020 Q1 |
| Royal Bank OF Canada | 104.0k | 0.08% | $12.1M | added +21.9% | ≤2013 |
Largest 50 of 322 shown; the full ranked, searchable register is at boothcheck.com/holders/WLK. 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.