What Is an Employee Stock Option (ESO)?
An employee stock option gives you the right, but not the obligation, to buy company shares at a preset strike price, usually the stock's fair value on the grant date, once the option has vested. If the stock later trades above the strike, you can exercise, buying at the strike and capturing the spread; if it stays below, the option is worthless but costs you nothing.
Suppose you receive 10,000 options struck at $2 and the company later reaches $12 per share. Exercising costs $20,000 and yields stock worth $120,000, a $100,000 gain, whereas the same value delivered as RSUs would have had no upside leverage but also no risk of expiring worthless.
ISOs vs. NSOs and the Tax Maze
U.S. options come in two tax flavors. Incentive stock options (ISOs) can qualify for long-term capital gains treatment if you hold the shares at least two years from grant and one year from exercise, but the paper spread at exercise counts toward the alternative minimum tax. Non-qualified stock options (NSOs) are simpler: the spread at exercise is taxed as ordinary income immediately.
The AMT trap is real: exercising ISOs on a high-flying private stock can create a large tax bill on paper gains you cannot sell, and employees have owed six-figure taxes on shares that later collapsed. Model the tax impact, ideally with a professional, before any large exercise.
Startup Options in Practice
Options dominate startup pay because young companies have volatile, hard-to-value stock where leverage is attractive and cash is scarce. A typical grant vests over four years with a one-year cliff, and most companies give you only 90 days after leaving to exercise vested options or lose them, though some now offer extended windows.
Valuing them requires assumptions about exit price and dilution. If you hold 0.1% of a startup and it exits for $500 million, your stake is worth about $500,000 before taxes and dilution, but the realistic range of outcomes includes zero, so never count unexercised options as money in the bank.
Options vs. RSUs
RSUs deliver certain value with no leverage, while options deliver leveraged upside with a real chance of zero, which is why mature public companies grant RSUs and startups grant options. As companies grow, they usually migrate from options to RSUs.
If you can choose between them, a rough benchmark is that one RSU is worth three to four options at the same company, since the option only pays off above the strike. Weigh your risk tolerance and how concentrated your finances already are in your employer.
