The Post-Termination Exercise Window (PTEW) is the period after termination during which an employee can exercise vested stock options before they expire. It is set by the option plan and grant agreement, with 90 days as the standard default (driven by ISO tax law requiring exercise within 90 days of termination), with extended PTEWs of 5, 7, or 10 years increasingly offered as a recruiting differentiator. It is one of the most consequential terms in an option grant because it determines whether vested equity actually delivers economic value to the employee or evaporates into forfeiture.
The PTEW mechanic: