Stock Options

Quick Definition

A stock option is a contract granting the holder the right, but not the obligation, to buy (call option) or sell (put option) a specified number of shares at a predetermined price (the strike price) before or on a specified expiration date. Stock options exist in two distinct contexts: employee stock options granted by companies as compensation, and exchange-traded options bought and sold on financial markets. Both share the same underlying mechanics but serve different purposes and have different tax treatment.

What It Means

The word "option" is literal. You have a choice, not a requirement. A call option gives you the right to buy shares at the strike price regardless of how high the market price has risen. A put option gives you the right to sell shares at the strike price regardless of how far the market price has fallen.

This asymmetry is the defining feature of all options: your potential gain is unlimited (calls) or large (puts), while your potential loss is limited to the premium you paid for the option. This risk-reward profile attracts traders, hedgers, and income generators.

For employees receiving options as compensation, the logic is alignment. If the company's stock rises significantly, employees who hold options share in that wealth creation, which incentivizes performance and retention.

Part 1: Employee Stock Options (ESOs)

Types of Employee Stock Options

How Employee Stock Options Work

Grant: Company grants you options to buy 10,000 shares at $20 (the current price becomes the strike price).

Vesting: Options typically vest over 4 years with a 1-year cliff:

• Year 1 cliff: 25% (2,500 shares) vest all at once
• Years 2-4: 1/48th per month (approximately 208 shares/month)

Exercise window: Once vested, you can exercise (buy shares at $20). Most grants have a 10-year window.

Expiration: Options not exercised by the end of the 10-year window expire worthless. Employees leaving the company typically have 90 days to exercise vested options.

The Economic Payoff

Scenario: You received 10,000 options at $20 strike, fully vested. Stock is now $50.

The spread ($50 minus $20 = $30 per share) is the option's intrinsic value.

ISO vs. NSO Tax Treatment

ISO qualifying disposition requirements:

1. Sell at least 2 years after the grant date
2. Sell at least 1 year after the exercise date

Meeting both thresholds converts the entire gain to long-term capital gains, potentially saving 15-20% or more in taxes compared to ordinary income rates.

The AMT Trap with ISOs: Worse in 2026

Exercising ISOs does not trigger regular income tax. But the spread between your strike price and the fair market value at exercise is included in your Alternative Minimum Tax calculation. In a year you exercise large ISOs, you may owe significant AMT, even if you do not sell a single share.

The One Big Beautiful Bill Act (OBBBA), signed July 4, 2025, made this trap more dangerous for 2026 and beyond. Two changes matter:

1. AMT exemption phaseout starts earlier: The exemption begins phasing out at $500,000 of AMT income for single filers and $1,000,000 for married filing jointly. These thresholds are down sharply from 2025.
2. Phaseout rate doubled: The exemption now phases out at 50 cents on the dollar, double the prior 25% rate. A married couple's exemption is fully eliminated near $1.28 million of AMT income, versus about $1.8 million under the old rules.

For 2026, the AMT exemption is $90,100 (single) and $140,200 (MFJ). AMT rates remain 26% on AMT income below $239,100 and 28% above.

What this means in practice: A large ISO exercise stacked on top of a strong income year is more likely to trigger AMT in 2026 than it would have been before. The AMT-safe window for ISO exercises is materially narrower. Someone exercising ISOs at a newly public company, where the spread can be enormous, needs to model the AMT impact before exercising.

The classic ISO trap: exercise late in the year, hold for qualifying disposition, pay AMT on phantom income, then watch the stock decline. You owe tax on value that evaporated. Some tech workers in the 2000-2002 dotcom bust and the 2022 selloff lost their entire net worth this way. The 83(b) election can help in early-exercise scenarios, but it must be filed within 30 days of grant, with no extensions.

Startup Employee Options: A Real-World Scenario

You joined a startup in 2020, receiving 100,000 options at $1.00 strike (409A valuation).

Value at exercise: 100,000 x ($50.00 minus $1.00) = $4,900,000 gain

Tax treatment depends on whether you exercised ISOs or NSOs, when you exercised, and your other income. The SpaceX IPO in June 2026, the largest in history, created exactly this kind of scenario for thousands of employees holding ISOs. Understanding the mechanics before you exercise is critical. Read more in our guide to equity and stock options at work.

Part 2: Exchange-Traded Options

The Basics

Exchange-traded options are standardized contracts traded on options exchanges (CBOE, NYSE Arca, Nasdaq PHLX). Standard terms:

• 1 contract = 100 shares of the underlying
• Strikes available at regular intervals (e.g., every $5 or $10)
• Expirations: Weekly, monthly (third Friday), quarterly, LEAPS (1-3 years)

Calls vs. Puts

Call Option Example

Buy 1 XYZ $100 call for $5 (expiring in 30 days). Stock currently at $98.

Break-even = strike + premium = $100 + $5 = $105

Common Options Strategies

Options Pricing: What Drives Option Value

Time decay (theta) is the key force destroying option buyer value. Options lose value every day from the passage of time, all else equal. This is why options sellers (who collect premium) often favor time passing, while buyers need the stock to move quickly.

Key Points to Remember

• Employee stock options give workers the right to buy company stock at the grant price, which becomes valuable if the stock rises above that price
• ISOs get favorable capital gains treatment if holding periods are met; NSOs trigger ordinary income tax at exercise
• The AMT trap with ISOs is a serious risk, and OBBBA made it worse for 2026 by lowering phaseout thresholds and doubling the phaseout rate
• Exchange-traded options: calls profit when stock rises above strike + premium; puts profit when stock falls below strike minus premium
• Theta decay erodes option value daily. Buyers need moves to happen quickly; sellers are paid to wait
• The maximum loss for an option buyer is always limited to the premium paid; sellers can face unlimited losses on naked calls

Common Mistakes to Avoid

• Letting options expire unexercised: Vested employee options with intrinsic value will expire at termination or at the end of the 10-year window. Always track and exercise before expiration.
• Exercising ISOs without modeling AMT: The 2026 AMT phaseout changes mean a large ISO exercise is more likely to trigger AMT than in prior years. Model your liability before exercising, especially in a year with other income or an IPO event.
• Buying out-of-the-money options near expiration: Short-dated out-of-the-money options are lottery tickets with extremely low probability of profit.
• Selling naked calls without understanding risk: Selling uncovered call options has unlimited theoretical loss. The stock can rise to any price.
• Forgetting the $100,000 ISO annual limit: Under IRC Section 422(d), only $100,000 of ISO stock (measured at grant-date fair market value) can first become exercisable in any calendar year. Excess ISOs automatically convert to NSO treatment.

Frequently Asked Questions

Q: What happens to my stock options if my company gets acquired? A: It depends on the acquisition terms. In most acquisitions, unvested options either accelerate (all vest immediately), are assumed by the acquirer (convert to acquirer options at an exchange ratio), or are canceled with a cash payment equal to the spread. Vested options are typically cashed out at the acquisition price minus strike price. Your grant agreement and the merger agreement will specify exact treatment. Read these carefully before an acquisition.

Q: Should I exercise employee stock options as soon as they vest? A: Not automatically. Key factors: (1) What is your confidence in the company's growth? (2) Can you afford to hold the shares if the price falls after exercise? (3) For ISOs, have you modeled the AMT impact under the new 2026 rules? (4) What is the company's liquidity path? For public company options with significant intrinsic value, many advisors recommend a systematic exercise strategy rather than all-or-nothing decisions.

Q: What is the difference between stock options and restricted stock units (RSUs)? A: Stock options give you the right to buy shares at a fixed price. They have value only if the stock exceeds the strike price. RSUs are grants of shares that vest over time. They always have value equal to the current share price. RSUs are simpler and guaranteed to have value (as long as the company has any value). Options offer more leverage upside but can expire worthless if the stock never exceeds the strike price. Most large tech companies have shifted compensation toward RSUs over options.

Q: How did the 2025 tax law (OBBBA) change ISO planning? A: The OBBBA made the TCJA tax rates and brackets permanent, which provides certainty. But it also lowered the AMT exemption phaseout thresholds to $500,000 (single) and $1,000,000 (MFJ), and doubled the phaseout rate from 25% to 50%. This means the AMT-safe window for ISO exercises is narrower in 2026. If you are planning a large ISO exercise, especially in an IPO year, consult a tax professional who can model your specific AMT exposure.

Sources: IRS Revenue Procedure 2025-32, myStockOptions.com analysis of OBBBA, and the One Big Beautiful Bill Act (P.L. 119-21). Consult a tax professional for your specific situation.