NET Power Inc. filed an 8-K on November 10, 2026, disclosing that its Board of Directors approved an amendment to the stock option held by President and Chief Operating Officer Marc Horstman, changing post-termination exercise rights effective November 4, 2026.

Key Highlights

  • Option holder: Marc Horstman, President and Chief Operating Officer of NET Power Inc.
  • Option details: 240,000 shares of Class A Common Stock at an exercise price of $2.13 per share, granted June 2, 2025, fully vested June 2, 2026, expiring June 2, 2030.
  • Key change - non-cause termination: Following a company-initiated termination other than for cause, the option now continues to vest on its original schedule and remains exercisable until its expiration date.
  • Key change - resignation: The post-resignation exercise window is extended from 30 days to 90 days, subject to the expiration date.
  • Termination for cause: The option terminates immediately, whether or not vested, with no exercise period.
  • Unchanged elements: The amendment does not alter the number of shares, exercise price, vesting schedule, or expiration date of the option.
  • Broader applicability: The Option Amendment applies to time-vesting stock options granted under the NET Power Inc. 2023 Omnibus Incentive Plan on the standard form, excluding holders who resigned before the Compensation Committee adopted it in October 2026.

Board Approval of Option Amendment for COO Marc Horstman

According to the filing, the Board of Directors of NET Power Inc. (NYSE:NPWR) approved on November 4, 2026, the application of an Option Amendment to the stock option held by Marc Horstman, the company's President and Chief Operating Officer. The Compensation Committee had adopted the Option Amendment in October 2026, and it became effective as to Mr. Horstman's option upon the Board's approval on that date.

The filing describes how the amendment modifies post-termination exercise rights compared to the prior standard form. Under the previous terms, the company disclosed, an option terminated immediately following a company-initiated termination of service for any reason other than death or disability, regardless of vesting status, and a resigning holder had only 30 days to exercise the vested portion. Under the amended terms, a termination by the company other than for cause allows the option to continue vesting on its original schedule and to be exercised, to the extent vested, through the original expiration date. A resignation now permits a 90-day post-separation exercise window rather than 30 days, though not beyond the expiration date. Death or disability treatment is unchanged, and a termination for cause results in immediate forfeiture.

The filing notes that Mr. Horstman's specific option covers 240,000 shares of Class A Common Stock at an exercise price of $2.13 per share, was granted on June 2, 2025, became fully vested on June 2, 2026, and expires on June 2, 2030. The company stated that the full text of the Option Amendment is intended to be filed as an exhibit to its Quarterly Report on Form 10-Q for the quarter ended September 30, 2026.

What Was Disclosed

NET Power Inc. disclosed a Board-approved amendment to the post-termination exercise provisions of COO Marc Horstman's stock option covering 240,000 shares at $2.13 per share, extending rights after non-cause termination and resignation while leaving core option terms unchanged.