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 ($10.8m this quarter). Holder counts are more reliable. Shares outstanding: 128.3m as of 2025-10-24, 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 ≈ $73.96. Options: 9 managers hold calls ($18.4m notional), 10 hold puts ($51.2m).
Trends to Q4 2025
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 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q1 2024 | 159 | 170 |
| Q2 2024 | 187 | 164 |
| Q3 2024 | 210 | 170 |
| Q4 2024 | 174 | 195 |
| Q1 2025 | 183 | 175 |
| Q2 2025 | 168 | 200 |
| Q3 2025 | 158 | 160 |
| Q4 2025 | 143 | 176 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q1 2025 | $3.0m | $68.4m | 23.18 |
| Q2 2025 | $19.5m | $58.1m | 2.98 |
| Q3 2025 | $19.3m | $57.8m | 2.99 |
| Q4 2025 | $18.4m | $51.2m | 2.78 |
Biggest buyers
| WELLINGTON MANAGEMENT GROUP LLP | Added | +4.2m |
| Capital World Investors | New | +2.2m |
| DIMENSIONAL FUND ADVISORS LP | Added | +585.4k |
| VANGUARD GROUP INC | Added | +477.7k |
| Orbis Allan Gray Ltd | Added | +472.2k |
| Woodline Partners LP | Added | +434.4k |
| Holocene Advisors, LP | Added | +366.4k |
| D. E. Shaw & Co., Inc. | Added | +326.3k |
| MILLENNIUM MANAGEMENT LLC | Added | +321.4k |
| Engineers Gate Manager LP | New | +289.3k |
Biggest sellers
| VICTORY CAPITAL MANAGEMENT INC | Reduced | -1.8m |
| CITADEL ADVISORS LLC | Reduced | -997.5k |
| Balyasny Asset Management L.P. | Sold out | -475.7k |
| Caisse de depot et placement du Quebec | Sold out | -368.3k |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP | Sold out | -299.7k |
| GOLDMAN SACHS GROUP INC | Reduced | -297.4k |
| ROYAL BANK OF CANADA | Reduced | -296.3k |
| SCHRODER INVESTMENT MANAGEMENT GROUP | Sold out | -261.6k |
| JPMORGAN CHASE & CO | Reduced | -248.3k |
| JACOBS LEVY EQUITY MANAGEMENT, INC | Reduced | -192.3k |
Biggest calls
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $4.4m59.8k shares |
| CITADEL ADVISORS LLC | Added | $4.3m58.6k shares |
| Twin Tree Management, LP | Added | $2.9m39.0k shares |
| Walleye Capital LLC | Added | $2.5m34.0k shares |
| Walleye Trading LLC | Added | $1.8m24.8k shares |
| JANE STREET GROUP, LLC | Added | $1.7m23.0k shares |
| TUDOR INVESTMENT CORP ET AL | Reduced | $244.0k3.3k shares |
| GROUP ONE TRADING LLC | Added | $229.2k3.1k shares |
| SIMPLEX TRADING, LLC | Reduced | $229.2k3.1k shares |
Biggest puts
| JANE STREET GROUP, LLC | Added | $38.7m523.9k shares |
| CITADEL ADVISORS LLC | Added | $7.8m104.9k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $2.0m26.8k shares |
| Walleye Trading LLC | Reduced | $776.4k10.5k shares |
| Walleye Capital LLC | Reduced | $502.8k6.8k shares |
| D. E. Shaw & Co., Inc. | New | $488.0k6.6k shares |
| Twin Tree Management, LP | New | $406.7k5.5k shares |
| SIMPLEX TRADING, LLC | Added | $266.2k3.6k shares |
| TWO SIGMA INVESTMENTS, LP | New | $214.4k2.9k shares |
| GROUP ONE TRADING LLC | New | $59.2k800 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 in Q4 2025
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 |
|---|---|---|---|---|---|
| Q1 2024 | 0 | — | 2 | $1.9m | — |
| Q2 2024 | 0 | — | 2 | $1.3m | — |
| Q3 2024 | 0 | — | 0 | — | — |
| 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 | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2025-12-22 | Chao Albert Executive Chairman, director | Sold | $3.0m40.8k 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, Q4 2025
| Manager | Shares | Change |
|---|---|---|
| Orbis Allan Gray Ltd 1.36% of their portfolio | 4.4m $324.3m | Added +472.2k |
| WELLINGTON MANAGEMENT GROUP LLP 0.05% of their portfolio | 4.2m $312.1m | Added +4.2m |
| VANGUARD GROUP INC 0.00% of their portfolio | 3.9m $289.6m | Added +477.7k |
| BlackRock, Inc. 0.00% of their portfolio | 3.3m $241.2m | Added +75.7k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.02% of their portfolio | 2.2m $163.3m | Added +572 |
| Capital World Investors 0.02% of their portfolio | 2.2m $160.5m | New |
| DIMENSIONAL FUND ADVISORS LP 0.03% of their portfolio | 1.9m $139.4m | Added +585.4k |
| BRANDES INVESTMENT PARTNERS, LP 0.94% of their portfolio | 1.7m $123.5m | Added +121.6k |
| STATE STREET CORP 0.00% of their portfolio | 1.4m $103.3m | Added +101.4k |
| Holocene Advisors, LP 0.19% of their portfolio | 1.2m $90.3m | Added +366.4k |
| VICTORY CAPITAL MANAGEMENT INC 0.05% of their portfolio | 1.1m $82.4m | Reduced -1.8m |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.01% of their portfolio | 924.7k $68.4m | Added +7.4k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.10% of their portfolio | 876.9k $64.8m | Added +20.9k |
| MORGAN STANLEY 0.00% of their portfolio | 759.6k $56.2m | Reduced -56.0k |
| GOLDMAN SACHS GROUP INC 0.01% of their portfolio | 754.0k $55.7m | Reduced -297.4k |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.19% of their portfolio | 668.4k $49.4m | Reduced -192.3k |
| Nuveen, LLC 0.01% of their portfolio | 652.9k $48.3m | Reduced -33.6k |
| UBS Group AG 0.01% of their portfolio | 648.0k $47.9m | Added +87.5k |
| Woodline Partners LP 0.18% of their portfolio | 628.2k $46.4m | Added +434.4k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 594.9k $44.0m | Reduced -58.2k |
| THOMPSON SIEGEL & WALMSLEY LLC 0.67% of their portfolio | 536.3k $39.7m | Added +95.0k |
| Allspring Global Investments Holdings, LLC 0.06% of their portfolio | 506.8k $37.6m | Reduced -39.4k |
| D. E. Shaw & Co., Inc. 0.03% of their portfolio | 486.3k $36.0m | Added +326.3k |
| ProShare Advisors LLC 0.06% of their portfolio | 435.3k $32.2m | Added +12.6k |
| MILLENNIUM MANAGEMENT LLC 0.02% of their portfolio | 427.8k $31.6m | Added +321.4k |
| Erste Asset Management GmbH 0.26% of their portfolio | 420.0k $31.1m | Added +160.0k |
| ANTIPODES PARTNERS Ltd 0.65% of their portfolio | 416.5k $30.8m | Reduced -139.4k |
| Merewether Investment Management, LP 0.66% of their portfolio | 388.1k $28.7m | Added +119.7k |
| VOLORIDGE INVESTMENT MANAGEMENT, LLC 0.09% of their portfolio | 349.0k $25.8m | Reduced -45.4k |
| JANUS HENDERSON GROUP PLC 0.01% of their portfolio | 334.6k $24.7m | Reduced -31.4k |
| NEW YORK STATE COMMON RETIREMENT FUND 0.03% of their portfolio | 309.6k $22.9m | Unchanged |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 297.2k $22.0m | Added +24.3k |
| Engineers Gate Manager LP 0.25% of their portfolio | 289.3k $21.4m | New |
| NORTHERN TRUST CORP 0.00% of their portfolio | 268.6k $19.9m | Added +30.5k |
| ROBOTTI ROBERT 3.40% of their portfolio | 256.2k $18.9m | Added +74.4k |
| VAN LANSCHOT KEMPEN INVESTMENT MANAGEMENT N.V. 0.15% of their portfolio | 235.9k $17.4m | Added +39.9k |
| Ceredex Value Advisors LLC 0.52% of their portfolio | 235.6k $17.4m | New |
| FMR LLC 0.00% of their portfolio | 228.8k $16.9m | Reduced -85.5k |
| Invesco Ltd. 0.00% of their portfolio | 213.2k $15.8m | Added +78.5k |
| DEPRINCE RACE & ZOLLO INC 0.29% of their portfolio | 204.2k $15.1m | Added +15.2k |
| CITADEL ADVISORS LLC 0.01% of their portfolio | 203.3k $15.0m | Reduced -997.5k |
| TWO SIGMA INVESTMENTS, LP 0.02% of their portfolio | 198.4k $14.7m | Added +95.4k |
| Diamond Hill Capital Management, LLC (Investment Advisor) 0.07% of their portfolio | 190.2k $14.1m | New |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 184.4k $13.6m | Reduced -24.5k |
| NORGES BANK 0.00% of their portfolio | 181.3k $13.4m | Not comparable |
| Bank of New York Mellon Corp 0.00% of their portfolio | 174.3k $12.9m | Reduced -3.7k |
| TEACHERS RETIREMENT SYSTEM OF THE STATE OF KENTUCKY 0.09% of their portfolio | 165.3k $12.2m | Unchanged |
| Russell Investments Group, Ltd. 0.01% of their portfolio | 158.3k $11.7m | Reduced -26.3k |
| ExodusPoint Capital Management, LP 0.13% of their portfolio | 154.4k $11.4m | New |
| FIRST TRUST ADVISORS LP 0.01% of their portfolio | 146.4k $10.8m | Reduced -18.5k |
| TWO SIGMA ADVISERS, LP 0.02% of their portfolio | 144.7k $10.7m | Added +71.0k |
| SPROTT INC. 0.37% of their portfolio | 140.0k $10.4m | Added +10.0k |
| Cerity Partners LLC 0.01% of their portfolio | 127.1k $9.4m | Added +44.0k |
| Quantinno Capital Management LP 0.02% of their portfolio | 116.4k $8.6m | Added +51.1k |
| Thomist Capital Management, LP 2.28% of their portfolio | 111.9k $8.4m | Added +65.7k |
| FEDERATED HERMES, INC. 0.01% of their portfolio | 107.7k $8.0m | Added +104.7k |
| Alyeska Investment Group, L.P. 0.02% of their portfolio | 103.0k $7.6m | Reduced -16.9k |
| Corient Private Wealth LP 0.01% of their portfolio | 101.4k $7.5m | Added +68.4k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 92.2k $6.8m | Reduced -98.7k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 91.9k $6.8m | Reduced -5.2k |
| NATIXIS 0.03% of their portfolio | 87.9k $6.5m | New |
| RHUMBLINE ADVISERS 0.01% of their portfolio | 85.4k $6.3m | Reduced -3.4k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 85.3k $6.3m | Reduced -296.3k |
| Swiss National Bank 0.00% of their portfolio | 75.9k $5.6m | New |
| Recurrent Investment Advisors LLC 0.41% of their portfolio | 75.6k $5.6m | Added +57.5k |
| Select Equity Group, L.P. 0.03% of their portfolio | 75.0k $5.5m | New |
| LAZARD ASSET MANAGEMENT LLC 0.01% of their portfolio | 74.4k $5.5m | Added +1.8k |
| AGMAN CAPITAL LLC 4.55% of their portfolio | 72.3k $5.3m | First filing |
| PRINCIPAL FINANCIAL GROUP INC 0.00% of their portfolio | 71.7k $5.3m | Reduced -2.4k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 68.4k $5.1m | Added +1.7k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 67.3k $5.0m | Reduced -248.3k |
| BARCLAYS PLC 0.00% of their portfolio | 66.6k $4.9m | Reduced -35.0k |
| PDT Partners, LLC 0.31% of their portfolio | 65.0k $4.8m | Added +45.5k |
| Jain Global LLC 0.04% of their portfolio | 62.0k $4.6m | Added +49.6k |
| Legal & General Group Plc 0.00% of their portfolio | 57.3k $4.2m | Added +20.6k |
| HITE Hedge Asset Management LLC 0.25% of their portfolio | 52.2k $3.9m | Reduced -47.8k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 49.1k $3.6m | Reduced -35.3k |
| Walleye Capital LLC 0.02% of their portfolio | 47.7k $3.5m | Reduced -100.7k |
| California Public Employees Retirement System 0.00% of their portfolio | 46.8k $3.5m | Reduced -24 |
| WEDGE CAPITAL MANAGEMENT L L P/NC 0.06% of their portfolio | 42.8k $3.2m | Added +3.5k |
| Retirement Systems of Alabama 0.01% of their portfolio | 40.0k $3.0m | Reduced -288 |
| Quantbot Technologies LP 0.10% of their portfolio | 39.6k $2.9m | Reduced -17.2k |
| SG Americas Securities, LLC 0.00% of their portfolio | 37.0k $2.7m | Added +30.1k |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 36.1k $2.7m | Added +34.0k |
| VARCOV Co. 1.04% of their portfolio | 35.6k $2.6m | First filing |
| LUMINUS MANAGEMENT LLC 2.40% of their portfolio | 35.2k $2.6m | New |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 33.5k $2.5m | Added +5.4k |
| Hudson Bay Capital Management LP 0.01% of their portfolio | 30.4k $2.3m | Added +26.9k |
| COMERICA BANK 0.01% of their portfolio | 28.5k $2.1m | Added +221 |
| SEI INVESTMENTS CO 0.00% of their portfolio | 28.4k $2.1m | Added +13.7k |
| ENVESTNET ASSET MANAGEMENT INC 0.00% of their portfolio | 27.9k $2.1m | Added +424 |
| Aventail Capital Group, LP 0.12% of their portfolio | 27.8k $2.1m | Reduced -50.6k |
| CITIGROUP INC 0.00% of their portfolio | 27.3k $2.0m | Reduced -89.8k |
| BANK OF MONTREAL /CAN/ 0.00% of their portfolio | 26.9k $2.0m | Reduced -18.2k |
| Verition Fund Management LLC 0.01% of their portfolio | 26.1k $1.9m | Reduced -1.1k |
| STATE OF WISCONSIN INVESTMENT BOARD 0.00% of their portfolio | 25.7k $1.9m | New |
| OCCUDO QUANTITATIVE STRATEGIES LP 0.12% of their portfolio | 25.2k $1.9m | Reduced -2.2k |
| STATE BOARD OF ADMINISTRATION OF FLORIDA RETIREMENT SYSTEM 0.00% of their portfolio | 24.1k $1.8m | Unchanged |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 23.8k $1.8m | Added +15.0k |
| AMG National Trust Bank 0.04% of their portfolio | 23.3k $1.7m | New |