WLK

SEC source: 0001567619-20-006977 · doc1.xml · nonDerivative · entry 4

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,965,277

F4 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $37.43 to $37.87, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F5 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006977 · doc1.xml · nonDerivative · entry 3

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,950,246

F3 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $36.42 to $37.42, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F5 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006977 · doc1.xml · nonDerivative · entry 2

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,882,434

F2 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $35.41 to $36.41, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F5 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006977 · doc1.xml · nonDerivative · entry 1

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,825,015

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $34.30 to $35.30, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F5 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-015789 · doc1.xml · nonDerivative · entry 6

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 960,000

F8 · price: Reflects the average price of shares purchased March 24, 2020. Each line in Table I of the original Form 4, filed March 25, 2020, correctly aggregated purchases within a $1.00 price range.

F2 · balance_after: Amended to reflect total direct ownership of Issuer shares as of the original Form 4 filing date. Purchases reported on and after March 16, 2020 were erroneously added to existing indirect holdings. These indirect holdings of 46,005,227 (which correspond to a post stock-split total of 92,010,554 shares) are owned by TTWF LP and further described by footnote 12 below.

F3 · ownership.direct: Erroneously reported as indirect holdings. Amended to reflect direct ownership.

SEC source: 0001567619-20-006808 · doc1.xml · nonDerivative · entry 5

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,820,277

F5 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $38.78 to $39.77, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006808 · doc1.xml · nonDerivative · entry 4

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,798,500

F4 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $37.77 to $38.77, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006808 · doc1.xml · nonDerivative · entry 2

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,680,776

F2 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $35.71 to $36.65, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006808 · doc1.xml · nonDerivative · entry 1

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,658,279

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $34.69 to $35.69, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-015789 · doc1.xml · nonDerivative · entry 5

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 815,000

F7 · price: Reflects the average price of shares purchased March 19, 2020 Each line in Table I of the original Form 4, filed March 20, 2020, correctly aggregated purchases within a $1.00 price range.

F2 · balance_after: Amended to reflect total direct ownership of Issuer shares as of the original Form 4 filing date. Purchases reported on and after March 16, 2020 were erroneously added to existing indirect holdings. These indirect holdings of 46,005,227 (which correspond to a post stock-split total of 92,010,554 shares) are owned by TTWF LP and further described by footnote 12 below.

F3 · ownership.direct: Erroneously reported as indirect holdings. Amended to reflect direct ownership.

SEC source: 0001567619-20-006727 · doc1.xml · nonDerivative · entry 4

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,655,277

F4 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $32.94 to $33.29, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F5 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006727 · doc1.xml · nonDerivative · entry 3

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,652,977

F3 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $31.87 to $32.78, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F5 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006727 · doc1.xml · nonDerivative · entry 2

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,616,187

F2 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $30.86 to $31.86, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F5 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006727 · doc1.xml · nonDerivative · entry 1

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,516,247

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $29.85 to $30.85, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F5 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006808 · doc1.xml · nonDerivative · entry 3

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,744,112

F3 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $36.75 to $37.75, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-015789 · doc1.xml · nonDerivative · entry 4

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 650,000

F6 · price: Reflects the average price of shares purchased March 18, 2020. Each line in Table I of the original Form 4, filed March 19, 2020, correctly aggregated purchases within a $1.00 price range.

F2 · balance_after: Amended to reflect total direct ownership of Issuer shares as of the original Form 4 filing date. Purchases reported on and after March 16, 2020 were erroneously added to existing indirect holdings. These indirect holdings of 46,005,227 (which correspond to a post stock-split total of 92,010,554 shares) are owned by TTWF LP and further described by footnote 12 below.

F3 · ownership.direct: Erroneously reported as indirect holdings. Amended to reflect direct ownership.

SEC source: 0001567619-20-006641 · doc1.xml · nonDerivative · entry 6

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,490,277

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006641 · doc1.xml · nonDerivative · entry 5

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,490,177

F5 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $34.00 to $34.98, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006641 · doc1.xml · nonDerivative · entry 4

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,447,356

F4 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $32.99 to $33.99, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006641 · doc1.xml · nonDerivative · entry 3

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,378,353

F3 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $31.98 to $32.98, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006641 · doc1.xml · nonDerivative · entry 2

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,337,277

F2 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $30.97 to $31.97, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006641 · doc1.xml · nonDerivative · entry 1

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,334,437

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $29.90 to $30.77, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F6 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-015789 · doc1.xml · nonDerivative · entry 3

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 485,000

F5 · price: Reflects the average price of shares purchased March 17, 2020. Each line in Table I of the original Form 4, filed March 18, 2020, correctly aggregated purchases within a $1.00 price range.

F2 · balance_after: Amended to reflect total direct ownership of Issuer shares as of the original Form 4 filing date. Purchases reported on and after March 16, 2020 were erroneously added to existing indirect holdings. These indirect holdings of 46,005,227 (which correspond to a post stock-split total of 92,010,554 shares) are owned by TTWF LP and further described by footnote 12 below.

F3 · ownership.direct: Erroneously reported as indirect holdings. Amended to reflect direct ownership.

SEC source: 0001567619-20-006510 · doc1.xml · nonDerivative · entry 3

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,325,277

F3 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $32.41 to $32.82, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F4 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006510 · doc1.xml · nonDerivative · entry 2

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,312,952

F2 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $31.40 to $32.40, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F4 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006510 · doc1.xml · nonDerivative · entry 1

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,255,749

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $30.39 to $31.39, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F4 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006508 · doc1.xml · nonDerivative · entry 1

Kearns Roger L. · CIK 0001739128 · EVP, Vinyls Chemicals

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 14,224

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $29.84 to $29.91, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

SEC source: 0001567619-20-015789 · doc1.xml · nonDerivative · entry 2

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 320,000

F4 · price: Reflects the average price of shares purchased March 16, 2020. Each line in Table I of the original Form 4, filed March 17, 2020, correctly aggregated purchases within a $1.00 price range.

F2 · balance_after: Amended to reflect total direct ownership of Issuer shares as of the original Form 4 filing date. Purchases reported on and after March 16, 2020 were erroneously added to existing indirect holdings. These indirect holdings of 46,005,227 (which correspond to a post stock-split total of 92,010,554 shares) are owned by TTWF LP and further described by footnote 12 below.

F3 · ownership.direct: Erroneously reported as indirect holdings. Amended to reflect direct ownership.

SEC source: 0001567619-20-006376 · doc1.xml · nonDerivative · entry 2

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,165,277

F2 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $33.18 to $34.00, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F3 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-006376 · doc1.xml · nonDerivative · entry 1

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 46,119,014

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $23.17 to $33.17, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F3 · ownership.nature: TTWFGP LLC is the general partner of TTWF LP, the record holder of the securities listed in Table 1. Reporting Person has no direct pecuniary interest in the securities in Table 1. Reporting Person may be deemed to beneficially own an indirect pecuniary interest in the securities in Table 1.

SEC source: 0001567619-20-015789 · doc1.xml · nonDerivative · entry 1

TTWFGP LLC · CIK 0001299599 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 160,000

F1 · price: Reflects the average price of shares purchased March 13, 2020. Each line in Table I of the original Form 4, filed March 16, 2020, correctly aggregated purchases within a $1.00 price range.

F2 · balance_after: Amended to reflect total direct ownership of Issuer shares as of the original Form 4 filing date. Purchases reported on and after March 16, 2020 were erroneously added to existing indirect holdings. These indirect holdings of 46,005,227 (which correspond to a post stock-split total of 92,010,554 shares) are owned by TTWF LP and further described by footnote 12 below.

F3 · ownership.direct: Erroneously reported as indirect holdings. Amended to reflect direct ownership.

SEC source: 0001567619-20-004940 · doc1.xml · derivative · entry 3

Chao Albert · CIK 0001299403 · Director · President & CEO · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 57,800 shares

Expires 2020-02-26

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: The stock options are excercisable in three equal installments on February 26, 2011, 2012 and 2013.

SEC source: 0001567619-21-004978 · doc1.xml · derivative · entry 10

Teel Lawrence E. · CIK 0001551480 · EVP and Special Advisor to CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 6,928 shares

Expires 2027-02-17

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: The stock options are excercisable in three installments of 33%, 33% and 34% on February 17, 2018, 2019 and 2020.

SEC source: 0001567619-21-004978 · doc1.xml · derivative · entry 9

Teel Lawrence E. · CIK 0001551480 · EVP and Special Advisor to CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,996

Underlying: Common Stock · 9,698 shares

Expires 2029-02-15

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: The stock options are excercisable in three installments of 33%, 33% and 34% on February 15, 2020, 2021 and 2022.

SEC source: 0001567619-21-004978 · doc1.xml · derivative · entry 8

Teel Lawrence E. · CIK 0001551480 · EVP and Special Advisor to CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 15,961

Underlying: Common Stock · 7,861 shares

Expires 2030-02-14

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: The stock options are excercisable in three installments of 33%, 33% and 34% on February 14, 2021, 2022 and 2023.

SEC source: 0001567619-21-004978 · doc1.xml · derivative · entry 7

Teel Lawrence E. · CIK 0001551480 · EVP and Special Advisor to CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 4,060 shares

Expires 2026-02-18

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: The stock options are excercisable in three installments of 33%, 33% and 34% on February 18, 2017, 2018 and 2019.

SEC source: 0001567619-20-004651 · doc1.xml · derivative · entry 4

Chao Albert · CIK 0001299403 · Director · President & CEO · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 57,800

Underlying: Common Stock · 68,698 shares

Expires 2020-02-26

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: The stock options are excercisable in three equal installments on February 26, 2011, 2012 and 2013.

SEC source: 0001567619-20-004651 · doc1.xml · nonDerivative · entry 2

Chao Albert · CIK 0001299403 · Director · President & CEO · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 369,856

F1 · kind: A portion of the sale proceeds were used to cover the strike price and related taxes in regards to the excercise of the options disclosed in Table II.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $62.15 to $62.72, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.

SEC source: 0001567619-20-004651 · doc1.xml · nonDerivative · entry 1

Chao Albert · CIK 0001299403 · Director · President & CEO · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 421,448

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001567619-20-004940 · doc1.xml · nonDerivative · entry 1

Chao Albert · CIK 0001299403 · Director · President & CEO · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 427,656

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001567619-20-004287 · doc1.xml · nonDerivative · entry 2

Buesinger Robert F. · CIK 0001488587 · EVP, Vinyl Products

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 10,569

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $60.50 to $60.873, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.

SEC source: 0001567619-20-004290 · doc1.xml · nonDerivative · entry 2

Kenner Andrew · CIK 0001439749 · SVP - Chemical Manufacturing

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,361

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $60.50 to $60.946, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.

SEC source: 0001567619-20-004289 · doc1.xml · nonDerivative · entry 3

Chao James · CIK 0001299505 · Director · Chairman · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 74,869

SEC source: 0001567619-20-004289 · doc1.xml · nonDerivative · entry 2

Chao James · CIK 0001299505 · Director · Chairman · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 75,142

SEC source: 0001567619-20-004288 · doc1.xml · nonDerivative · entry 3

Chao Albert · CIK 0001299403 · Director · President & CEO · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 352,750

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $61.14 to $61.80, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.

SEC source: 0001567619-20-004288 · doc1.xml · nonDerivative · entry 2

Chao Albert · CIK 0001299403 · Director · President & CEO · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 353,130

SEC source: 0001567619-20-004291 · doc1.xml · nonDerivative · entry 3

Mangieri George J · CIK 0001298504 · VP & Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,671

SEC source: 0001567619-20-004291 · doc1.xml · nonDerivative · entry 2

Mangieri George J · CIK 0001298504 · VP & Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,695

SEC source: 0001567619-20-004292 · doc1.xml · nonDerivative · entry 3

Teel Lawrence E. · CIK 0001551480 · EVP, Olefins

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,292

SEC source: 0001567619-20-004292 · doc1.xml · nonDerivative · entry 2

Teel Lawrence E. · CIK 0001551480 · EVP, Olefins

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,338