WESTLAKE CORPORATION WLK
COM · Common Stock · CUSIP 960413102 · ISIN US9604131022
American petrochemical company
- SectorMaterials
- IndustryIndustrial Organic Chemicals
- HeadquartersHouston, TX
- Founded1986
- Websitewestlake.com
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($18.6m this quarter). Holder counts are more reliable. Shares outstanding: 127.8m as of 2026-07-29, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $73.11. Options: 5 managers hold calls ($12.6m notional), 6 hold puts ($5.8m).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 321 |
| Q4 2022 | 343 |
| Q1 2023 | 342 |
| Q2 2023 | 340 |
| Q3 2023 | 335 |
| Q4 2023 | 357 |
| Q1 2024 | 347 |
| Q2 2024 | 382 |
| Q3 2024 | 403 |
| Q4 2024 | 378 |
| Q1 2025 | 362 |
| Q2 2025 | 308 |
| Q3 2025 | 305 |
| Q4 2025 | 298 |
| Q1 2026 | 339 |
| Q2 2026 | 358 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q3 2024 | 210 | 170 |
| Q4 2024 | 174 | 195 |
| Q1 2025 | 183 | 175 |
| Q2 2025 | 168 | 200 |
| Q3 2025 | 158 | 160 |
| Q4 2025 | 143 | 176 |
| Q1 2026 | 203 | 132 |
| Q2 2026 | 188 | 183 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $19.3m | $57.8m | 2.99 |
| Q4 2025 | $18.4m | $51.2m | 2.78 |
| Q1 2026 | $26.7m | $16.9m | 0.63 |
| Q2 2026 | $12.6m | $5.8m | 0.46 |
Biggest buyers
| AQR CAPITAL MANAGEMENT LLC | Added | +1.3m |
| DIMENSIONAL FUND ADVISORS LP | Added | +585.5k |
| JACOBS LEVY EQUITY MANAGEMENT, INC | Added | +360.3k |
| CITADEL ADVISORS LLC | Added | +339.3k |
| ExodusPoint Capital Management, LP | New | +327.2k |
| Qube Research & Technologies Ltd | New | +321.7k |
| MILLENNIUM MANAGEMENT LLC | Added | +281.1k |
| Balyasny Asset Management L.P. | Added | +256.2k |
| BlackRock, Inc. | Added | +215.1k |
| Susquehanna Portfolio Strategies, LLC | Added | +212.0k |
Biggest sellers
| Orbis Allan Gray Ltd | Reduced | -3.2m |
| WELLINGTON MANAGEMENT GROUP LLP | Reduced | -1.7m |
| Capital World Investors | Reduced | -1.4m |
| FMR LLC | Reduced | -951.2k |
| Holocene Advisors, LP | Sold out | -730.0k |
| UBS Group AG | Reduced | -379.6k |
| BRANDES INVESTMENT PARTNERS, LP | Reduced | -269.7k |
| NEW YORK STATE COMMON RETIREMENT FUND | Reduced | -268.7k |
| FEDERATED HERMES, INC. | Reduced | -264.1k |
| DEPRINCE RACE & ZOLLO INC | Sold out | -203.4k |
Biggest calls
| CITADEL ADVISORS LLC | Added | $5.4m73.8k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $5.0m68.1k shares |
| JANE STREET GROUP, LLC | Added | $1.5m20.0k shares |
| GROUP ONE TRADING LLC | Reduced | $408.8k5.6k shares |
| SIMPLEX TRADING, LLC | Reduced | $335.8k4.6k shares |
Biggest puts
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $3.2m44.0k shares |
| CITADEL ADVISORS LLC | Reduced | $1.7m22.8k shares |
| JANE STREET GROUP, LLC | Reduced | $678.9k9.3k shares |
| Twin Tree Management, LP | Reduced | $240.9k3.3k shares |
| GROUP ONE TRADING LLC | Reduced | $21.9k300 shares |
| SIMPLEX TRADING, LLC | Reduced | $21.9k300 shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 0 | — | 1 | $453.4k | — |
| Q1 2025 | 0 | — | 0 | — | — |
| Q2 2025 | 1 | $7.8k | 1 | $6.0k | — |
| Q3 2025 | 0 | — | 0 | — | — |
| Q4 2025 | 0 | — | 1 | $3.0m | — |
| Q1 2026 | 0 | — | 2 | $4.1m | — |
| Q2 2026 | 0 | — | 0 | — | — |
| Q3 2026 | 0 | — | 1 | $3.1m | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-08-11 | Chao Albert Executive Chairman, director | Sold | $3.1m38.9k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 3.3m $240.5m | Added +215.1k |
| Capital World Investors 0.02% of their portfolio | 2.8m $207.5m | Reduced -1.4m |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.02% of their portfolio | 2.2m $161.1m | Reduced -200.8k |
| Orbis Allan Gray Ltd 0.52% of their portfolio | 2.1m $152.2m | Reduced -3.2m |
| DIMENSIONAL FUND ADVISORS LP 0.03% of their portfolio | 2.1m $149.8m | Added +585.5k |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.01% of their portfolio | 1.8m $127.9m | Reduced -17.2k |
| BRANDES INVESTMENT PARTNERS, LP 0.80% of their portfolio | 1.6m $114.8m | Reduced -269.7k |
| AQR CAPITAL MANAGEMENT LLC 0.04% of their portfolio | 1.6m $114.6m | Added +1.3m |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 1.5m $106.9m | Added +8.6k |
| STATE STREET CORP 0.00% of their portfolio | 1.5m $106.1m | Added +72.9k |
| GOLDMAN SACHS GROUP INC 0.01% of their portfolio | 1.3m $93.5m | Reduced -112.5k |
| CITADEL ADVISORS LLC 0.04% of their portfolio | 1.1m $77.0m | Added +339.3k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.09% of their portfolio | 1.0m $74.7m | Added +79.4k |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.01% of their portfolio | 817.2k $59.7m | Reduced -164.2k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 718.6k $52.5m | Added +104.3k |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.19% of their portfolio | 709.4k $51.8m | Added +360.3k |
| Balyasny Asset Management L.P. 0.08% of their portfolio | 625.9k $45.7m | Added +256.2k |
| Woodline Partners LP 0.10% of their portfolio | 452.0k $33.0m | Added +114.9k |
| Nuveen, LLC 0.01% of their portfolio | 446.5k $32.6m | Reduced -118.3k |
| MORGAN STANLEY 0.00% of their portfolio | 437.6k $31.9m | Reduced -48.9k |
| UBS Group AG 0.01% of their portfolio | 431.6k $31.5m | Reduced -379.6k |
| SCHRODER INVESTMENT MANAGEMENT GROUP 0.02% of their portfolio | 375.9k $28.1m | Added +1.4k |
| MILLENNIUM MANAGEMENT LLC 0.02% of their portfolio | 366.1k $26.7m | Added +281.1k |
| FMR LLC 0.00% of their portfolio | 361.2k $26.4m | Reduced -951.2k |
| ExodusPoint Capital Management, LP 0.22% of their portfolio | 327.2k $23.9m | New |
| Qube Research & Technologies Ltd 0.03% of their portfolio | 321.7k $23.5m | New |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 318.8k $23.3m | Added +7.1k |
| Erste Asset Management GmbH 0.18% of their portfolio | 305.0k $22.8m | Reduced -90.0k |
| VAN LANSCHOT KEMPEN INVESTMENT MANAGEMENT N.V. 0.15% of their portfolio | 268.4k $19.6m | Added +24.1k |
| Jupiter Topco LLC 0.01% of their portfolio | 267.7k $19.5m | First filing |
| NORTHERN TRUST CORP 0.00% of their portfolio | 262.9k $19.2m | Reduced -6.2k |
| ROBOTTI ROBERT 2.77% of their portfolio | 235.4k $17.2m | Added +90.4k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 232.2k $17.0m | Reduced -4.8k |
| Susquehanna Portfolio Strategies, LLC 0.27% of their portfolio | 230.4k $16.8m | Added +212.0k |
| ProShare Advisors LLC 0.02% of their portfolio | 228.3k $16.7m | Reduced -67.5k |
| NORGES BANK 0.00% of their portfolio | 214.1k $15.6m | Not comparable |
| Jump Financial, LLC 0.14% of their portfolio | 209.9k $15.3m | New |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 209.7k $15.3m | Added +4.0k |
| D. E. Shaw & Co., Inc. 0.01% of their portfolio | 200.5k $14.6m | Reduced -32.6k |
| Russell Investments Group, Ltd. 0.01% of their portfolio | 194.4k $14.2m | Added +105.0k |
| Invesco Ltd. 0.00% of their portfolio | 191.0k $13.9m | Added +11.5k |
| Cerity Partners LLC 0.01% of their portfolio | 166.4k $12.1m | Added +93.8k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 163.5k $11.9m | Reduced -17.6k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 163.3k $12.3m | Added +65.5k |
| Allspring Global Investments Holdings, LLC 0.02% of their portfolio | 163.1k $11.9m | Reduced -122.4k |
| SPROTT INC. 0.39% of their portfolio | 160.1k $11.7m | Added +27.5k |
| TEACHERS RETIREMENT SYSTEM OF THE STATE OF KENTUCKY 0.08% of their portfolio | 156.8k $11.4m | Reduced -21.4k |
| Campbell & CO Investment Adviser LLC 0.57% of their portfolio | 148.2k $10.8m | New |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 141.8k $10.4m | Reduced -1.7m |
| Lighthouse Investment Partners, LLC 0.31% of their portfolio | 135.4k $9.9m | New |
| Recurrent Investment Advisors LLC 0.58% of their portfolio | 128.8k $9.4m | Added +16.0k |
| Quantinno Capital Management LP 0.01% of their portfolio | 123.2k $9.0m | Added +1.8k |
| HRT FINANCIAL LP 0.02% of their portfolio | 116.4k $8.5m | New |
| MARSHALL WACE, LLP 0.01% of their portfolio | 111.6k $8.1m | New |
| TUDOR INVESTMENT CORP ET AL 0.03% of their portfolio | 110.7k $8.1m | New |
| Assenagon Asset Management S.A. 0.01% of their portfolio | 110.6k $8.1m | New |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 105.9k $7.7m | Reduced -769 |
| MACKENZIE FINANCIAL CORP 0.01% of their portfolio | 104.9k $7.7m | Added +32.9k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 96.8k $7.1m | Reduced -7.2k |
| Thomist Capital Management, LP 2.59% of their portfolio | 96.2k $7.0m | Added +23.2k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 94.4k $6.9m | Added +87.7k |
| Point72 Asset Management, L.P. 0.01% of their portfolio | 89.7k $6.6m | New |
| Alberta Investment Management Corp 0.04% of their portfolio | 89.2k $6.5m | New |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 86.3k $6.3m | Reduced -999 |
| Walleye Capital LLC 0.03% of their portfolio | 82.8k $6.0m | Added +23.0k |
| Meiji Yasuda Asset Management Co Ltd. 0.27% of their portfolio | 82.8k $6.0m | Added +3.3k |
| Squarepoint Ops LLC 0.01% of their portfolio | 80.0k $5.8m | Added +41.4k |
| NATIXIS 0.03% of their portfolio | 77.1k $5.6m | New |
| Tidal Investments LLC 0.01% of their portfolio | 76.1k $5.6m | Added +28.2k |
| PDT Partners, LLC 0.29% of their portfolio | 75.8k $5.5m | Unchanged |
| PRINCIPAL FINANCIAL GROUP INC 0.00% of their portfolio | 75.7k $5.5m | Added +1.2k |
| AGMAN CAPITAL LLC 3.29% of their portfolio | 71.5k $5.2m | Reduced -818 |
| Engineers Gate Manager LP 0.07% of their portfolio | 71.3k $5.2m | Added +28.8k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 66.0k $7.7m | Reduced -1.3k |
| Swiss National Bank 0.00% of their portfolio | 64.2k $4.7m | Reduced -11.7k |
| SG Americas Securities, LLC 0.00% of their portfolio | 59.1k $4.3m | Added +34.5k |
| Turas Capital Management LP 1.97% of their portfolio | 58.8k $4.3m | New |
| Merewether Investment Management, LP 0.07% of their portfolio | 53.4k $3.9m | Reduced -166.5k |
| AXQ CAPITAL, LP 0.41% of their portfolio | 51.4k $3.8m | New |
| Legal & General Group Plc 0.00% of their portfolio | 50.0k $3.7m | Reduced -712 |
| Mariner, LLC 0.00% of their portfolio | 47.3k $3.5m | New |
| TWO SIGMA INVESTMENTS, LP 0.00% of their portfolio | 45.4k $3.3m | New |
| BI Asset Management Fondsmaeglerselskab A/S 0.02% of their portfolio | 41.8k $3.1m | Reduced -252 |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 40.9k $3.0m | Reduced -268.7k |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 37.2k $2.7m | Added +3.9k |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 36.9k $2.7m | Reduced -7.6k |
| CITIGROUP INC 0.00% of their portfolio | 36.6k $2.7m | Reduced -18.0k |
| STATE OF WISCONSIN INVESTMENT BOARD 0.01% of their portfolio | 35.8k $2.6m | Added +10.6k |
| OCCUDO QUANTITATIVE STRATEGIES LP 0.14% of their portfolio | 35.7k $2.6m | Reduced -8.7k |
| BANK OF MONTREAL /CAN/ 0.00% of their portfolio | 35.6k $2.6m | Reduced -3.4k |
| HITE Hedge Asset Management LLC 0.14% of their portfolio | 34.6k $2.5m | New |
| ACADIAN ASSET MANAGEMENT LLC 0.00% of their portfolio | 34.5k $2.5m | New |
| Retirement Systems of Alabama 0.01% of their portfolio | 34.5k $2.5m | Reduced -6.4k |
| LOS ANGELES CAPITAL MANAGEMENT LLC 0.01% of their portfolio | 32.6k $2.4m | Added +32.4k |
| ABN AMRO INVESTMENT SOLUTIONS 0.02% of their portfolio | 31.6k $2.3m | New |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 31.3k $2.3m | Added +2.8k |
| WORLDQUANT MILLENNIUM ADVISORS LLC 0.01% of their portfolio | 31.2k $2.3m | Added +12.8k |
| VANGUARD ASSET MANAGEMENT, Ltd 0.00% of their portfolio | 30.0k $2.2m | Reduced -3.3k |
| ENVESTNET ASSET MANAGEMENT INC 0.00% of their portfolio | 29.6k $2.2m | Added +1.5k |
| FIRST TRUST ADVISORS LP 0.00% of their portfolio | 27.5k $2.0m | Reduced -74.8k |