IOSP

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $76.555 to $77.0713. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $75.5001 to $76.55. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $75.5001 to $76.55. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $75.5001 to $76.55. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Shares withheld to settle income tax liability incurred upon vesting of restricted stock unit award on February 27, 2026.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $76.555 to $77.0713. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $76.555 to $77.0713. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Shares withheld to settle income tax liability incurred upon vesting of restricted stock unit award on February 27, 2026.

Shares withheld to settle income tax liability incurred upon vesting of restricted stock unit award on February 27, 2026.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $76.555 to $77.0713. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Shares withheld to settle income tax liability incurred upon vesting of restricted stock unit award on February 27, 2026.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $76.555 to $77.0713. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $75.5001 to $76.55. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

This Form 4/A amends the Form 4 filed on March 3, 2026 to correct the transaction price reported in Table I. The price reported reflects the weighted average sale price. The shares were sold in multiple transactions at prices ranging from $75.5001 to $76.55. The reporting person undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Represents Restricted Stock Units ("RSUs") granted on February 23, 2026 which vest in full on February 23, 2029.

Each share of phantom stock is the economic equivalent of one share of Innospec common stock. The award is scheduled to automatically settle in cash on the Expiration Date based on the closing price of Innospec common stock on that date.

Represents Restricted Stock Units ("RSUs") vesting in full on February 23, 2029, granted by Issuer in connection with Reporting Person's service as a non-employee director.

Represents Restricted Stock Units ("RSUs") granted on February 23, 2026 which vest in full on February 23, 2029.

Represents Restricted Stock Units ("RSUs") vesting in full on February 23, 2029, granted by Issuer in connection with Reporting Person's service as a non-employee director.

Represents Restricted Stock Units ("RSUs") granted on February 23, 2026 which vest in full on February 23, 2029.

Represents Restricted Stock Units ("RSUs") vesting in full on February 23, 2029, granted by Issuer in connection with Reporting Person's service as a non-employee director.

Represents Restricted Stock Units ("RSUs") vesting in full on February 23, 2029, granted by Issuer in connection with Reporting Person's service as a non-employee director.

Represents Restricted Stock Units ("RSUs") granted on February 23, 2026 which vest in full on February 23, 2029.

Represents Restricted Stock Units ("RSUs") vesting in full on February 23, 2029, granted by Issuer in connection with Reporting Person's service as a non-employee director.

Represents Restricted Stock Units ("RSUs") granted on February 23, 2026 which vest in full on February 23, 2029.

Represents Restricted Stock Units ("RSUs") vesting in full on February 23, 2029, granted by Issuer in connection with Reporting Person's service as a non-employee director.

Each share of phantom stock is the economic equivalent of one share of Innospec common stock. The award is scheduled to automatically settle in cash on the Expiration Date based on the closing price of Innospec common stock on that date.

Shares of common stock acquired upon settlement of a performance-based restricted stock unit award granted to the reporting person on February 27, 2023.

Shares of common stock acquired upon settlement of a performance-based restricted stock unit award granted to the reporting person on February 27, 2023.

Shares of common stock acquired upon settlement of a performance-based restricted stock unit award granted to the reporting person on February 27, 2023.

Shares of common stock acquired upon settlement of a performance-based restricted stock unit award granted to the reporting person on February 27, 2023.

Shares of common stock acquired upon settlement of a performance-based restricted stock unit award granted to the reporting person on February 27, 2023.

Shares withheld to settle income tax liability incurred upon vesting of the above-referenced restricted stock unit award on May 13, 2025; not an open market transaction.

Shares sold through a "broker sale" to settle tax withholding obligations in connection with the vesting of time-based restricted stock units.

Shares sold through a "broker sale" to settle tax withholding obligations in connection with the vesting of time-based restricted stock units.

Shares withheld to settle income tax liability incurred upon vesting of the above-referenced restricted stock unit award on May 13, 2025; not an open market transaction.

Shares withheld to settle income tax liability incurred upon vesting of restricted stock unit award on February 21, 2025.

Each share of phantom stock is the economic equivalent of one share of Innospec common stock. The award is settled in cash on the Expiration Date based on the closing price of Innospec stock on that date.

Represents Restricted Stock Units ("RSUs") granted on February 24, 2025 which vest in full on February 24, 2028.

Represents Restricted Stock Units ("RSUs") vesting in full on February 24, 2028, granted by Issuer in connection with Reporting Person's service as a non-employee director.