What Is a Stock Option (Employee)? How They Work and Why They Matter

Written by Jim Norris · NorrisAI AlphaLens · Updated August 2026

Quick answer: Employee stock options give employees the right to buy company shares at a fixed price (the exercise or strike price) for a set period, typically after a vesting period. They're a form of compensation that aligns employee incentives with shareholders — employees benefit only when the stock rises. For investors, options are important because they represent potential future dilution that reduces per-share value, and because the size of option grants relative to shares outstanding reveals how generously (or excessively) management compensates itself and employees.

How employee stock options work

An employee receives options to buy 10,000 shares at $50 (the strike price, typically the market price on grant date) with a 4-year vesting schedule (25% per year) and a 10-year expiration.

After year 1, 2,500 options vest. If the stock is at $80, the employee can exercise those options — paying $50 per share and immediately owning shares worth $80. The $30 "spread" is their economic gain.

If the stock is below $50 at any point before expiration, the options are "underwater" — there's no financial incentive to exercise. The options expire worthless if the stock never recovers above the strike price.

Why options matter for investors: dilution

When employees exercise options, new shares are issued — diluting existing shareholders. A company with 100 million shares outstanding and 10 million options outstanding has potential diluted shares of 110 million. Per-share valuation metrics — EPS, revenue per share, book value per share — should use diluted share counts that include all "in the money" options and other dilutive securities.

Always use diluted share counts when calculating per-share metrics. The difference between basic and diluted EPS reveals the dilution cost of the option program.

Stock-based compensation (SBC) — the accounting issue

Under current GAAP, stock-based compensation is an expense on the income statement — the fair value of options granted is expensed over the vesting period. Many companies report "adjusted earnings" that exclude SBC, arguing it's non-cash and therefore shouldn't count.

This is misleading. Stock-based compensation is a real economic cost — it transfers value from existing shareholders to employees through dilution. A company that pays $500 million in annual SBC is spending $500 million on employee compensation — the fact that it comes in the form of shares rather than cash doesn't make it less real.

When comparing companies on an adjusted earnings basis, always check whether SBC is excluded — and add it back to evaluate true compensation costs.

Warren Buffett has been explicit that stock-based compensation is a real expense and should be treated as such — arguing that if options aren't compensation, what are they? And if compensation isn't an expense, what is it? The practice of excluding SBC from adjusted earnings is one of the most widespread earnings manipulations in US corporate reporting.

RSUs vs options — the evolution of equity compensation

Many companies have shifted from options to Restricted Stock Units (RSUs) as their primary equity compensation vehicle. RSUs vest and deliver shares directly — unlike options, they have value even if the stock price is flat or declining from the grant date.

RSUs represent a larger guaranteed transfer of value from shareholders to employees than options — which only have value if the stock rises. High RSU grant rates relative to shares outstanding indicate significant ongoing dilution regardless of stock performance.

Professor Aswath Damodaran of NYU Stern Business School treats stock-based compensation as an operating expense in his valuation models — arguing that any valuation that excludes SBC from expenses is simply understating the true cost structure of the business. Companies where SBC represents 10%+ of revenue are paying a very high price for talent that must be factored into sustainable margin assessments. — Investment Valuation, Wiley

How AlphaLens handles stock-based compensation

The Earnings Quality Analyzer (framework #4) specifically checks whether SBC is being excluded from adjusted earnings figures and quantifies the real compensation cost. The Management Quality Scorecard evaluates whether option and RSU grant patterns are reasonable relative to company size and performance, or indicate excessive self-enrichment. The Fair Value Stress Test uses diluted share counts that fully account for all outstanding options and RSUs.

Where to go deeper

For a detailed walkthrough of each research framework, see the complete guide to all 15 AlphaLens frameworks.

For definitions of investing terms, see the AlphaLens investing glossary.