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WLK · Westlake Corp

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Market Cap
$9.68B
Shares
127.80M

Institutional ownership from SEC Form 13F filings. Investment managers with more than $100 million in U.S. equities must disclose their positions every quarter, within 45 days of quarter-end, so the holdings shown can lag the market by up to a quarter.

Holders: 359
Total Value: $2,917,890,155
Total Shares: 39,971,116
Showing 1–100 of 365 holdings by value · page 1 of 4

Institutional Ownership Trend

26 quarters

Holder Concentration

Across 359 13F filers · Δ vs Mar 31, 2026
Top Holder
8.2%
Sep 2023 → Jun 2026 · range 8.2% – 12.4%
−3.7 pts
Top 5
31.2%
Sep 2023 → Jun 2026 · range 31.2% – 49.2%
−6.6 pts
Top 10
50.8%
Sep 2023 → Jun 2026 · range 50.8% – 64.3%
−4.8 pts
HHI
335
Sep 2023 → Jun 2026 · range 335 – 566
Broadly held−107

Quarterly Activity

vs Mar 31, 2026
New
87
Increased
108
Decreased
121
Sold Out
67
Unchanged
43
Holder count: +20
Institutional value: -43.8%
Shares held: -10.1%

Top Buyers

vs Mar 31, 2026
Institution Added Now Holds Open

Top Sellers

vs Mar 31, 2026
Institution Sold Now Holds Open

Top New Positions

vs Mar 31, 2026
Institution Acquired Value (USD) Open

Top Sold-Out Positions

vs Mar 31, 2026
Institution Previously Held Last Value (USD) Open
Showing 100 of 365
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Holder Value (USD) % of 13F Shares Open
Key facts CIK 1262823 CUSIP 960413102 13F (30d) 291 filings 270 filers Visit website Investor relations