In a stock option grant, what is the post-termination exercise window and why does it matter?

## What the window is An option grant gives a right to buy shares at a fixed strike. Vesting decides how much of that right you hold; the **post-termination exercise window** decides how long you keep it after you stop working there. When the window closes, unexercised vested options are typically forfeited — they simply cease to exist, along with everything the vesting table earned you. A window of roughly ninety days after the final day is the traditional shape and remains common. A number of companies have deliberately moved to much longer windows — several years is not unusual where they have — precisely because the short version is hard on employees. Both exist, neither is universal, and the only authority for your grant is its own plan documents. Note as well that plans commonly define different windows for different departure reasons, so "the window" may not be one number. ## Why a short window bites Three costs collide inside it. **Cash.** Exercising means paying the strike for every share you exercise, out of your own money, in a short period that often coincides with a job change. **Illiquidity.** At a private company, what you buy is usually not sellable. You have converted cash into a position you cannot exit, whose value depends on an outcome years away. **Tax.** In many places, exercising creates a taxable moment of its own, potentially on a gain you cannot sell anything to fund. The rules differ sharply by country, by region and by the option flavour, and they change; the general point is that the bill and the sale can be years apart. Anything more specific than that belongs with a tax professional who knows your circumstances. The combined effect is that a short window converts "I earned this equity" into "I have ninety days to decide whether to buy an illiquid asset with my own savings." That is a real decision, and it should not be discovered on the way out. ## Mark it on the vesting table The practical habit is to read the grant's vesting table row by row and annotate it twice: once at the cliff row, and once with the exercise window written beside it. The table tells you what you have earned; the window tells you the deadline attached to keeping it. Together they answer the only two questions that matter about an option grant over time — how much is mine, and until when? For a private-company option grant, add the same three facts as always: the strike, the fully diluted share count, and the window. The illustrative machine-learning infrastructure grant used elsewhere on this topic — 5,760 units on a four-year schedule, 1,440 at the twelve-month cliff row, then 120 a month, with invented figures showing shape only — becomes a very different proposition if the window after leaving is short, because everything vested by then converts into a cash decision rather than an asset. ## What to ask, and when Ask the compensation partner before signing, in the same breath as the grant type: - Is the exercise window after leaving a fixed period, and how long is it? - Does it differ depending on the reason for leaving? - Roughly what would exercising all vested options cost at the current strike? - Are there any programs — for example an internal liquidity event — through which employees have been able to sell? These are ordinary questions. A company that has thought about employee ownership answers them without friction; hesitation is worth noting, not as an accusation but as information about how the equity is likely to feel in practice. ## How it changes the decision A short window pushes weight back onto the cash components of an offer, because the equity carries an extra condition — that you either stay or find money at a moment of your choosing. A long window makes vested options behave much more like something you have actually earned. Neither is a reason on its own to take or refuse a role, but the difference is large enough that it belongs in the comparison rather than in the footnotes. ## Anti-patterns Assuming vested options are permanently yours is the central misconception. Its relatives: discovering the window during a resignation conversation, assuming every company now uses a long window because some publicly do, and assuming a window can be extended on request — extensions are governed by plan documents and are not usually a matter of goodwill.