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 ($6.1m this quarter). Holder counts are more reliable. Shares outstanding: 128.2m as of 2025-07-30, 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 ≈ $75.99. Options: 12 managers hold calls ($19.5m notional), 12 hold puts ($58.1m).
Trends to Q2 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 |
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 2023 | 124 | 182 |
| Q4 2023 | 145 | 165 |
| Q1 2024 | 159 | 170 |
| Q2 2024 | 187 | 164 |
| Q3 2024 | 210 | 170 |
| Q4 2024 | 174 | 195 |
| Q1 2025 | 183 | 175 |
| Q2 2025 | 168 | 200 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2024 | $25.3m | $97.7m | 3.86 |
| Q4 2024 | $14.2m | $67.6m | 4.76 |
| Q1 2025 | $3.0m | $68.4m | 23.18 |
| Q2 2025 | $19.5m | $58.1m | 2.98 |
Biggest buyers
| PRICE T ROWE ASSOCIATES INC /MD/ | Added | +2.0m |
| BRANDES INVESTMENT PARTNERS, LP | Added | +1.0m |
| NORGES BANK | Added | +1.0m |
| ANTIPODES PARTNERS Ltd | New | +823.2k |
| ROYAL BANK OF CANADA | Added | +398.3k |
| Engineers Gate Manager LP | Added | +348.3k |
| DIMENSIONAL FUND ADVISORS LP | Added | +335.5k |
| Woodline Partners LP | New | +327.3k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | +319.7k |
| NEW YORK STATE COMMON RETIREMENT FUND | Added | +292.5k |
Biggest sellers
| Capital World Investors | Sold out | -1.3m |
| CITADEL ADVISORS LLC | Reduced | -840.5k |
| Balyasny Asset Management L.P. | Reduced | -442.0k |
| Ilex Capital Partners (UK) LLP | Reduced | -425.4k |
| BlackRock, Inc. | Reduced | -331.7k |
| ExodusPoint Capital Management, LP | Reduced | -327.2k |
| STATE STREET CORP | Reduced | -237.9k |
| JANUS HENDERSON GROUP PLC | Reduced | -180.2k |
| VICTORY CAPITAL MANAGEMENT INC | Reduced | -178.3k |
| UBS Group AG | Reduced | -165.6k |
Biggest calls
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $8.6m113.6k shares |
| Walleye Capital LLC | New | $2.7m35.6k shares |
| CITADEL ADVISORS LLC | Added | $2.1m28.2k shares |
| SIMPLEX TRADING, LLC | Added | $1.7m22.2k shares |
| JANE STREET GROUP, LLC | New | $1.3m17.1k shares |
| Polymer Capital Management (US) LLC | New | $759.3k10.0k shares |
| Twin Tree Management, LP | New | $736.5k9.7k shares |
| Walleye Trading LLC | New | $660.6k8.7k shares |
| TUDOR INVESTMENT CORP ET AL | New | $561.9k7.4k shares |
| D. E. Shaw & Co., Inc. | New | $235.4k3.1k shares |
Biggest puts
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | New | $48.2m634.4k shares |
| Walleye Capital LLC | New | $3.4m44.7k shares |
| CITADEL ADVISORS LLC | Reduced | $3.4m44.5k shares |
| Walleye Trading LLC | New | $774.5k10.2k shares |
| TUDOR INVESTMENT CORP ET AL | New | $721.3k9.5k shares |
| WOLVERINE TRADING, LLC | Added | $601.5k7.9k shares |
| Polymer Capital Management (US) LLC | New | $569.5k7.5k shares |
| JANE STREET GROUP, LLC | Reduced | $280.9k3.7k shares |
| SIMPLEX TRADING, LLC | Added | $182.0k2.4k shares |
| Mercuria Capital Strategies, LLC | Unchanged | $18.3k2.0k 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 Q2 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 |
|---|---|---|---|---|---|
| Q3 2023 | 0 | — | 1 | $131.0k | — |
| Q4 2023 | 0 | — | 1 | $550.1k | — |
| 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 | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2025-05-27 | Buesinger Robert F. EVP, PEM Segment Head · by trust | Sold | $6.0k83 shares |
| 2025-04-22 | Buesinger Robert F. EVP, PEM Segment Head · by trust | Bought | $7.8k83 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 2025
| Manager | Shares | Change |
|---|---|---|
| VICTORY CAPITAL MANAGEMENT INC 0.18% of their portfolio | 3.7m $282.6m | Reduced -178.3k |
| VANGUARD GROUP INC 0.00% of their portfolio | 3.5m $267.5m | Reduced -27.5k |
| BlackRock, Inc. 0.00% of their portfolio | 3.3m $252.7m | Reduced -331.7k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.02% of their portfolio | 2.1m $156.3m | Added +2.0m |
| FMR LLC 0.01% of their portfolio | 1.6m $122.6m | Added +66.4k |
| BRANDES INVESTMENT PARTNERS, LP 1.00% of their portfolio | 1.5m $110.6m | Added +1.0m |
| STATE STREET CORP 0.00% of their portfolio | 1.4m $105.7m | Reduced -237.9k |
| NORGES BANK 0.01% of their portfolio | 1.4m $104.3m | Added +1.0m |
| DIMENSIONAL FUND ADVISORS LP 0.02% of their portfolio | 1.3m $96.8m | Added +335.5k |
| GOLDMAN SACHS GROUP INC 0.01% of their portfolio | 1.1m $80.4m | Added +17.8k |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.29% of their portfolio | 985.3k $74.8m | Added +209.5k |
| Nuveen, LLC 0.02% of their portfolio | 886.1k $67.3m | Added +156.6k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.12% of their portfolio | 844.1k $64.1m | Reduced -9.7k |
| ANTIPODES PARTNERS Ltd 1.94% of their portfolio | 823.2k $62.5m | New |
| MILLENNIUM MANAGEMENT LLC 0.05% of their portfolio | 789.8k $60.0m | Reduced -111.4k |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.01% of their portfolio | 651.8k $49.5m | Added +280.7k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 574.2k $43.6m | Reduced -2.5k |
| Allspring Global Investments Holdings, LLC 0.07% of their portfolio | 520.7k $41.9m | Reduced -31.0k |
| VOLORIDGE INVESTMENT MANAGEMENT, LLC 0.15% of their portfolio | 520.3k $39.5m | Added +173.3k |
| MORGAN STANLEY 0.00% of their portfolio | 462.5k $35.1m | Added +199.9k |
| UBS Group AG 0.01% of their portfolio | 443.5k $33.7m | Reduced -165.6k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 437.0k $33.2m | Added +398.3k |
| ProShare Advisors LLC 0.05% of their portfolio | 355.2k $27.0m | Added +94.8k |
| Engineers Gate Manager LP 0.33% of their portfolio | 351.0k $26.7m | Added +348.3k |
| D. E. Shaw & Co., Inc. 0.03% of their portfolio | 343.0k $26.0m | Added +114.6k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.04% of their portfolio | 330.8k $25.1m | Added +319.7k |
| Woodline Partners LP 0.13% of their portfolio | 327.3k $24.9m | New |
| NEW YORK STATE COMMON RETIREMENT FUND 0.03% of their portfolio | 306.4k $23.3m | Added +292.5k |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP 0.02% of their portfolio | 290.0k $22.0m | New |
| Ilex Capital Partners (UK) LLP 0.69% of their portfolio | 273.6k $20.8m | Reduced -425.4k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 256.8k $19.5m | Added +12.3k |
| DEPRINCE RACE & ZOLLO INC 0.40% of their portfolio | 253.4k $19.2m | Added +22.9k |
| SCHRODER INVESTMENT MANAGEMENT GROUP 0.02% of their portfolio | 249.0k $18.9m | Reduced -565 |
| Alyeska Investment Group, L.P. 0.06% of their portfolio | 238.1k $18.1m | Added +45.3k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 233.0k $17.7m | Reduced -81.7k |
| BANK OF MONTREAL /CAN/ 0.01% of their portfolio | 231.0k $17.5m | Added +20.8k |
| JANUS HENDERSON GROUP PLC 0.01% of their portfolio | 214.3k $16.3m | Reduced -180.2k |
| BNP PARIBAS FINANCIAL MARKETS 0.01% of their portfolio | 185.4k $14.1m | Added +159.0k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 184.3k $14.0m | Reduced -35.4k |
| VAN LANSCHOT KEMPEN INVESTMENT MANAGEMENT N.V. 0.13% of their portfolio | 182.9k $13.9m | New |
| ROBOTTI ROBERT 2.31% of their portfolio | 182.8k $13.8m | Added +18.1k |
| Erste Asset Management GmbH 0.11% of their portfolio | 171.5k $13.0m | Added +18.3k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 167.6k $12.7m | Added +38.6k |
| TWO SIGMA ADVISERS, LP 0.02% of their portfolio | 158.5k $12.0m | Reduced -7.6k |
| Holocene Advisors, LP 0.03% of their portfolio | 158.2k $12.0m | Added +59.1k |
| RENAISSANCE TECHNOLOGIES LLC 0.01% of their portfolio | 144.2k $10.9m | Reduced -135.9k |
| 1832 Asset Management L.P. 0.02% of their portfolio | 138.9k $10.5m | Reduced -14.8k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 138.7k $10.5m | Reduced -82.8k |
| Qube Research & Technologies Ltd 0.01% of their portfolio | 134.6k $10.2m | Added +18.8k |
| AQR CAPITAL MANAGEMENT LLC 0.01% of their portfolio | 133.4k $10.0m | Added +114.3k |
| WEDGE CAPITAL MANAGEMENT L L P/NC 0.18% of their portfolio | 132.4k $10.1m | Added +37.8k |
| Russell Investments Group, Ltd. 0.01% of their portfolio | 129.2k $9.8m | Added +12.6k |
| FIRST TRUST ADVISORS LP 0.01% of their portfolio | 127.9k $9.7m | Reduced -38.6k |
| SPROTT INC. 0.47% of their portfolio | 125.0k $9.5m | Added +35.0k |
| Invesco Ltd. 0.00% of their portfolio | 124.6k $9.5m | Reduced -9.8k |
| Man Group plc 0.02% of their portfolio | 124.2k $9.4m | Reduced -16.7k |
| TWO SIGMA INVESTMENTS, LP 0.02% of their portfolio | 122.1k $9.3m | Reduced -144.0k |
| HITE Hedge Asset Management LLC 0.50% of their portfolio | 114.5k $8.7m | Added +43.0k |
| Walleye Capital LLC 0.08% of their portfolio | 112.2k $8.5m | Added +77.8k |
| ING GROEP NV 0.05% of their portfolio | 111.4k $8.5m | Added +81.8k |
| TEACHERS RETIREMENT SYSTEM OF THE STATE OF KENTUCKY 0.06% of their portfolio | 105.0k $8.0m | Added +93.3k |
| Janney Montgomery Scott LLC 0.02% of their portfolio | 101.0k $7.7m | Added +39.8k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 99.5k $7.6m | Reduced -19.4k |
| Squarepoint Ops LLC 0.02% of their portfolio | 94.5k $7.2m | Reduced -137.6k |
| DARK FOREST CAPITAL MANAGEMENT LP 0.28% of their portfolio | 92.5k $7.0m | Added +83.5k |
| RHUMBLINE ADVISERS 0.01% of their portfolio | 90.6k $6.9m | Reduced -9.8k |
| ExodusPoint Capital Management, LP 0.08% of their portfolio | 90.6k $6.9m | Reduced -327.2k |
| Cerity Partners LLC 0.01% of their portfolio | 86.8k $6.6m | Added +11.9k |
| STOREBRAND ASSET MANAGEMENT AS 0.02% of their portfolio | 86.2k $6.5m | Reduced -20.6k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 85.4k $6.5m | Added +24.2k |
| Balyasny Asset Management L.P. 0.01% of their portfolio | 79.8k $6.1m | Reduced -442.0k |
| PRINCIPAL FINANCIAL GROUP INC 0.00% of their portfolio | 75.6k $5.7m | Reduced -1.4k |
| Legal & General Group Plc 0.00% of their portfolio | 75.1k $5.7m | Reduced -69.9k |
| LAZARD ASSET MANAGEMENT LLC 0.01% of their portfolio | 74.1k $5.6m | Reduced -37.4k |
| CITIGROUP INC 0.00% of their portfolio | 72.6k $5.5m | Added +44.4k |
| Thomist Capital Management, LP 3.29% of their portfolio | 71.6k $5.5m | Added +25.5k |
| BARCLAYS PLC 0.00% of their portfolio | 71.0k $5.4m | Reduced -35.8k |
| Amundi 0.00% of their portfolio | 69.7k $5.7m | Added +18.9k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 68.6k $5.2m | Added +144 |
| California Public Employees Retirement System 0.00% of their portfolio | 59.9k $4.5m | Added +1.0k |
| SG Americas Securities, LLC 0.02% of their portfolio | 54.5k $4.1m | Reduced -3.1k |
| JCP Investment Management, LLC 2.32% of their portfolio | 53.0k $4.0m | New |
| Concentric Capital Strategies, LP 0.23% of their portfolio | 52.9k $4.0m | New |
| CANADA PENSION PLAN INVESTMENT BOARD 0.00% of their portfolio | 49.3k $3.7m | Added +10.0k |
| KBC Group NV 0.01% of their portfolio | 48.0k $3.6m | Added +21.3k |
| Journey Advisory Group, LLC 0.26% of their portfolio | 44.8k $3.4m | New |
| Verition Fund Management LLC 0.02% of their portfolio | 41.9k $3.2m | Reduced -9.6k |
| Retirement Systems of Alabama 0.01% of their portfolio | 40.8k $3.1m | Added +22 |
| JANE STREET GROUP, LLC 0.00% of their portfolio | 34.4k $2.6m | Reduced -51.6k |
| COMERICA BANK 0.01% of their portfolio | 34.3k $2.6m | Added +3.7k |
| Y-Intercept (Hong Kong) Ltd 0.06% of their portfolio | 32.5k $2.5m | New |
| Quantinno Capital Management LP 0.01% of their portfolio | 30.2k $2.3m | Reduced -97.3k |
| Twin Tree Management, LP 0.06% of their portfolio | 29.4k $2.2m | New |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 28.1k $2.1m | Added +165 |
| State of Alaska, Department of Revenue 0.02% of their portfolio | 27.7k $2.1m | Reduced -180 |
| Brevan Howard Capital Management LP 0.02% of their portfolio | 26.8k $2.0m | Added +10.6k |
| STATE OF WISCONSIN INVESTMENT BOARD 0.00% of their portfolio | 26.0k $2.0m | Added +353 |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 25.8k $2.0m | Added +15.2k |
| Northeast Financial Consultants Inc 0.08% of their portfolio | 24.8k $1.9m | New |
| STATE BOARD OF ADMINISTRATION OF FLORIDA RETIREMENT SYSTEM 0.00% of their portfolio | 24.6k $1.9m | Reduced -3.3k |