KOP · Koppers Holdings Inc.

The dividend equivalent rights ("DERs") accrued with respect to additional restricted stock units ("RSUs") credited to the reporting person with respect to deferred compensation. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The dividend equivalent rights ("DERs") accrued with respect to additional restricted stock units ("RSUs") credited to the reporting person with respect to deferred compensation. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to deferred compensation. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The dividend equivalent rights ("DERs") accrued with respect to additional restricted stock units ("RSUs") credited to the reporting person with respect to deferred compensation. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.88 to $41.53, inclusive. The reporting person undertakes to provide to the Securities and Exchange Commission, the issuer or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price.

The reporting person was awarded time-based restricted stock units on May 26, 2026, which will vest in four annual installments of 25 percent beginning January 5, 2027.

Includes 496 shares of Koppers Holdings Inc. common stock acquired pursuant to the Koppers Holdings Inc. Employee Stock Purchase Plan on March 31, 2026. These acquisitions were exempt under both Rule 16b-3(c) and Rule 16b-3(d).

The reporting person was awarded time-based restricted stock units on May 12, 2026, which will vest in full on May 12, 2029.

Restricted Stock Units ("RSUs") represent the right to receive shares of common stock on a one-for-one basis.

The RSUs become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

RSUs represent the right to receive shares of common stock on a one-for-one basis.

The RSUs become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

These DERs were released in connection with the vesting of RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Represents shares acquired upon release of dividend equivalent rights ("DERs"), as reported in Table II, on a one-for-one basis.

Restricted Stock Units ("RSUs") represent the right to receive shares of common stock on a one-for-one basis.

The RSUs become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The reporting person was awarded time-based restricted stock units.

These DERs were released in connection with the vesting of Restricted Stock Units (" RSUs") granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Represents shares acquired upon release of dividend equivalent rights ("DERs"), as reported in Table II, on a one-for-one basis.

The reporting person was awarded time-based restricted stock units ("RSUs").

These DERs were released in connection with the vesting of RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

These DERs were released in connection with the vesting of RSUs granted on November 5, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Represents shares acquired upon release of dividend equivalent rights ("DERs"), as reported in Table II, on a one-for-one basis.

Represents shares acquired upon release of dividend equivalent rights ("DERs"), as reported in Table II, on a one-for-one basis.

The reporting person was awarded time-based restricted stock units ("RSUs").

Represents shares acquired upon release of dividend equivalent rights ("DERs"), as reported in Table II, on a one-for-one basis.

These DERs were released in connection with the vesting of RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

The reporting person was awarded time-based restricted stock units ("RSUs").

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

The DERs accrued with respect to additional RSUs credited to the reporting person with respect to deferred compensation. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on November 5, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The DERs accrued with respect to additional RSUs credited to the reporting person with respect to deferred compensation. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The DERs accrued with respect to additional RSUs credited to the reporting person with respect to deferred compensation. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

The DERs accrued with respect to additional RSUs credited to the reporting person with respect to deferred compensation. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

Once released, the RSUs corresponding to these DERs will become payable according to the election of payment designation that was filed by the reporting person subject to the Koppers Holdings Inc. Director Deferred Compensation Plan (the "Plan"). Such payment will be either lump sum or in annual installments commencing on the May 31st next following the reporting person's separation from service (as defined under the Plan) or, if later, and elected by the reporting person at the time he/she first elects to defer any payment under the Plan, May 31st of the year specified by the reporting person.

The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $37.42 to $37.51, inclusive. The reporting person undertakes to provide to the Securities and Exchange Commission, the issuer or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price.

The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $36.22 to $37.16, inclusive. The reporting person undertakes to provide to the Securities and Exchange Commission, the issuer or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price.

Represents shares acquired upon release of dividend equivalent rights ("DERs"), as reported in Table II, on a one-for-one basis.

The DERs accrued with respect to additional PSUs credited to the reporting person with respect to PSUs granted on January 4, 2023. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock.

On January 4, 2023, the reporting person was granted performance share units ("PSUs") for which the performance criteria for the measurement period from January 1, 2023 through December 31, 2025 have been satisfied.

Shares surrendered to the issuer by the reporting person as payment for the tax withholding related to the vesting of PSUs.