CLIR · ClearSign Technologies Corp

The Issuer effected a reverse stock split of its outstanding common stock at a ratio of 1-for-10, effective as of 12:01 a.m., Eastern Time, on March 16, 2026.

The reporting person is the managing member of Otter Capital LLC.

As compensation for services as a non-employee director during the quarter ended June 30, 2026, the reporting person was granted non-statutory stock options to purchase 4,595 shares of common stock under the ClearSign Technologies Corporation Amended and Restated 2021 Equity Incentive Plan pursuant to the issuer's non-employee director compensation policy. These non-statutory stock options were immediately vested and exercisable on the grant date.

As compensation for services as a non-employee director during the quarter ended June 30, 2026, the reporting person was granted non-statutory stock options to purchase 4,595 shares of common stock under the Plan pursuant to the issuer's non-employee director compensation policy. These non-statutory stock options were immediately vested and exercisable on the grant date.

As compensation for services as a non-employee director during the quarter ended June 30, 2026, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation Amended and Restated 2021 Equity Incentive Plan (the "Plan") pursuant to the issuer's non-employee director compensation policy, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-employee director during the quarter ended June 30, 2026, the reporting person was granted non-statutory stock options to purchase 4,595 shares of common stock under the ClearSign Technologies Corporation Amended and Restated 2021 Equity Incentive Plan pursuant to the issuer's non-employee director compensation policy. These non-statutory stock options were immediately vested and exercisable on the grant date.

Represents the reporting person's two separate, open-market purchases of 1,000 shares of common stock of the issuer on April 23, 2026, at a price of $5.319 and $5.25 per share, respectively.

Represents the reporting person's two separate, open-market purchases of 1,000 shares of common stock of the issuer on April 23, 2026, at a price of $5.319 and $5.25 per share, respectively.

As compensation for services as a non-employee director during the quarter ended March 31, 2026, the reporting person was granted non-statutory stock options to purchase 3,024 shares of common stock under the ClearSign Technologies Corporation 2021 Equity Incentive Plan pursuant to the issuer's non-employee director compensation policy. These non-statutory stock options were immediately vested and exercisable on the grant date.

As compensation for services as a non-employee director during the quarter ended March 31, 2026, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan (the "Plan") pursuant to the issuer's non-employee director compensation policy, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-employee director during the quarter ended March 31, 2026, the reporting person was granted non-statutory stock options to purchase 3,024 shares of common stock under the Plan pursuant to the issuer's non-employee director compensation policy. These non-statutory stock options were immediately vested and exercisable on the grant date.

As compensation for services as a non-employee director during the quarter ended March 31, 2026, the reporting person was granted non-statutory stock options to purchase 3,024 shares of common stock under the ClearSign Technologies Corporation 2021 Equity Incentive Plan pursuant to the issuer's non-employee director compensation policy. These non-statutory stock options were immediately vested and exercisable on the grant date.

Represents the reporting person's open-market purchases of 2,000 shares of common stock of the issuer on March 16, 2026, and 2,000 shares of common stock of the issuer on March 17, 2026, at a price of $4.355 and $4.20 per share, respectively.

Represents the reporting person's open-market purchases of 2,000 shares of common stock of the issuer on March 16, 2026, and 2,000 shares of common stock of the issuer on March 17, 2026, at a price of $4.355 and $4.20 per share, respectively.

Represents a one-time bonus restricted stock units ("RSUs") grant to reporting person for services as an executive officer for the year ended December 31, 2025, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs granted on February 26, 2026, vest in three equal installments commencing on the first anniversary of the grant date.

On March 2, 2026, the reporting person filed a Form 4 reporting the receipt of 210,043 shares of the Issuer's common stock, on a pre-reverse stock split basis, as a one-time bonus grant for services as an executive officer for the year ended December 31, 2025 (the "Original Form 4"). This amendment to the Original Form 4 is being filed to correct (i) the number of shares received in connection with the reporting person's one-time bonus grant, (ii) the number of shares withheld for tax purposes, and (iii) the number of securities beneficially owned following such transactions. The number of shares withheld is based on the closing price of the Issuer's common stock on February 26, 2026, of $5.616, as adjusted for the 1-for-10 reverse stock split effected by the Issuer on March 16, 2026.

Amounts and price per share figures have been adjusted to reflect the 1-for-10 reverse stock split effected by the Issuer on March 16, 2026.

On March 2, 2026, the reporting person filed a Form 4 reporting the receipt of 210,043 shares of the Issuer's common stock, on a pre-reverse stock split basis, as a one-time bonus grant for services as an executive officer for the year ended December 31, 2025 (the "Original Form 4"). This amendment to the Original Form 4 is being filed to correct (i) the number of shares received in connection with the reporting person's one-time bonus grant, (ii) the number of shares withheld for tax purposes, and (iii) the number of securities beneficially owned following such transactions. The number of shares withheld is based on the closing price of the Issuer's common stock on February 26, 2026, of $5.616, as adjusted for the 1-for-10 reverse stock split effected by the Issuer on March 16, 2026.

Amounts and price per share figures have been adjusted to reflect the 1-for-10 reverse stock split effected by the Issuer on March 16, 2026.

Represents the payment of the reporting person's tax liability by withholding shares incident to the receipt of the Company's common stock issued on February 26, 2026, based on the closing price of the Company's common stock on February 26, 2026, of $0.5616.

Represents a one-time bonus grant to the reporting person for services as an executive officer for the year ended December 31, 2025, upon achievement of certain performance target metrics approved by the human capital and compensation committee of the board of directors. The number of shares awarded is based on the closing price of the Company's common stock on February 26, 2026, of $0.5616.

Reflects the vesting of 7,547 RSUs out of the 22,641 RSUs granted to the reporting person on February 22, 2024, into an equal number of shares of the Company's common stock, without the payment of any consideration, pursuant to the Company's 2021 Equity Incentive Plan.

On February 22, 2024, the reporting person was granted 22,641 RSUs as a one-time bonus for services as an executive officer for the year ended December 31, 2023, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs granted on February 22, 2024, vest in three equal installments that commenced on February 22, 2025.

Represents the payment of the reporting person's tax liability by withholding shares in connection with the vesting of 7,547 RSUs on February 22, 2026, and calculated based on the closing price of the Company's common stock, as reported on the Nasdaq Stock Market, on February 20, 2026, of $0.5949 (as February 22, 2026 fell on a weekend).

Reflects the vesting of 9,315 restricted stock units ("RSUs") out of the 27,946 RSUs granted to the reporting person on February 20, 2025, into an equal number of shares of the Company's common stock, without the payment of any consideration, pursuant to the Company's 2021 Equity Incentive Plan.

Represents the payment of the reporting person's tax liability by withholding shares in connection with the vesting of 9,315 RSUs on February 20, 2026, and calculated based on the closing price of the Company's common stock, as reported on the Nasdaq Stock Market, on February 20, 2026, of $0.5949.

On February 20, 2025, the reporting person was granted 27,946 RSUs as a one-time bonus for services as an executive officer for the year ended December 31, 2024, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs granted on February 20, 2025, vest in three equal installments that commenced on February 20, 2026.

On February 2, 2023, the reporting person was granted 30,380 RSUs as a one-time bonus for services as an executive officer for the year ended December 31, 2022, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs granted on February 2, 2023, vest in three equal installments that commenced on February 2, 2024.

Represents the payment of the reporting person's tax liability by withholding shares in connection with the vesting of 10,127 RSUs on February 2, 2026, and calculated based on the closing price of the Company's common stock, as reported on the Nasdaq Stock Market, on February 2, 2026, of $0.5991.

Reflects the vesting of 10,127 restricted stock units ("RSUs") out of the 30,380 RSUs granted to the reporting person on February 2, 2023, into an equal number of shares of the Company's common stock, without the payment of any consideration, pursuant to the Company's 2021 Equity Incentive Plan.

As compensation for services as a non-executive director during the quarter ending December 31, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending December 31, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending September 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending September 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending September 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending September 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending September 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan, pro-rated for the period beginning on July 1, 2025 and ending on July 25, 2025, the reporting person's last day of service as a non-executive director, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending June 30, 2025, on May 22, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan, pro-rated based on an appointment date of May 22, 2025, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending June 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending June 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending June 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

As compensation for services as a non-executive director during the quarter ending June 30, 2025, the reporting person was granted restricted stock units ("RSUs") under the ClearSign Technologies Corporation 2021 Equity Incentive Plan and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs will vest upon the first to occur of: (1) a Change in Control (as defined in the applicable RSU award agreement), (2) the reporting person's Disability (as defined in the applicable RSU award agreement); (3) the reporting person's death; or (4) the reporting person's separation from service.

On February 22, 2024, the reporting person was granted a one-time bonus of 22,641 RSUs, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs granted on February 22, 2024, vest in three equal annual installments that commenced on February 24, 2025.

Represents the payment of the reporting person's tax liability by withholding shares in connection with the vesting of 7,547 RSUs on February 24, 2025, and calculated based on the closing price of the Company's common stock, as reported on Nasdaq Stock Market, on February 24, 2025, of $0.7994.

Reflects the vesting of 7,547 restricted stock units ("RSUs") out of the 22,641 RSUs granted to the reporting person on February 22, 2024, into an equal number of shares of the Company's common stock, without the payment of any consideration, pursuant to the Company's 2021 Equity Incentive Plan.

Represents a one-time bonus grant to the reporting person for services as an executive officer for the year ended December 31, 2024. The number of shares awarded is based on the closing price of the Company's common stock on February 20, 2025, of $0.8588.

Represents the payment of the reporting person's tax liability by withholding shares incident to the receipt of the Company's common stock issued on February 20, 2025, based on the closing price of the Company's common stock on February 20, 2025, of $0.8588.

Represents a one-time bonus restricted stock units ("RSUs") grant to reporting person for services as an executive officer for the year ended December 31, 2024, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs granted on February 20, 2025, vest in three equal installments commencing on the first anniversary of the grant date.

Represents the payment of the reporting person's tax liability by withholding shares incident to the receipt of the Company's common stock issued on February 20, 2025, based on the closing price of the Company's common stock on February 20, 2025, of $0.8588.

Represents a one-time bonus grant to reporting person for services as an executive officer for the year ended December 31, 2024. The number of shares awarded is based on the closing price of the Company's common stock on February 20, 2025, of $0.8588.

Represents the payment of the reporting person's tax liability by withholding shares in connection with the vesting of 10,127 RSUs on February 2, 2025, and calculated based on the closing price of the Company's common stock, as reported on Nasdaq Stock Market, on February 2, 2025 of $1.20.

Reflects the vesting of 10,127 restricted stock units ("RSUs") out of the 30,380 RSUs granted to the reporting person on February 2, 2023, into an equal number of shares of the Company's common stock, without the payment of any consideration, pursuant to the 2021 Plan.

On February 2, 2023, the reporting person was granted a one-time bonus of 30,380 RSUs, and each RSU represents a right to receive one share of common stock or the cash equivalent thereof.

The RSUs granted on February 2, 2023, vest in three equal annual installments that commenced on February 2, 2024.