Sellers on secondary markets frequently describe their holdings in shorthand — 'I have options in the company' — without distinguishing between nonqualified stock options and incentive stock options. That distinction is not a formality. It determines whether your spread on exercise is taxed as ordinary income or deferred, and it shapes the entire tax profile of your secondary sale.
The core difference between NSOs and ISOs
A nonqualified stock option, or NSO, is the simpler of the two from a tax mechanics standpoint. When you exercise an NSO, the spread — the difference between the exercise price and the fair market value of the share on the date of exercise — is immediately treated as ordinary compensation income. Your employer withholds payroll taxes on that spread. Your cost basis in the acquired shares is then that fair market value at exercise. Any subsequent gain above that basis is taxed as capital gain, long-term if you hold the shares for more than one year after exercise.
An incentive stock option, or ISO, works differently. Exercise of an ISO does not produce ordinary income for regular income tax purposes. There is no withholding. The spread on exercise is, however, a preference item for the alternative minimum tax. Your regular income tax basis in shares acquired via ISO is the exercise price — not the fair market value at exercise. Qualifying disposition rules then determine how the eventual sale proceeds are taxed.
Why the secondary market complicates both paths
A secondary sale typically requires you to exercise your options before the transfer can close — or to sell already-exercised shares. In either case, you need to know exactly what type of option you hold and what the timeline implications are.
For NSO holders, the exercise-and-sell sequence on a secondary transaction is relatively predictable. You exercise, recognizing ordinary income on the spread. Your company withholds. You then immediately sell the shares in the secondary transaction, recognizing a short-term capital gain or loss equal to the difference between the secondary sale price and your FMV-at-exercise basis. Because the hold between exercise and sale is measured in days, the gain is almost always short-term, taxed at ordinary rates. The net effect is that most of your economic gain from the secondary is taxed as ordinary income, one way or another.
For ISO holders, the timing pressure is more acute. To achieve a qualifying disposition — and long-term capital gain treatment on the full spread — you must hold the shares for two years from the grant date and one year from the date of exercise. A secondary sale that closes within one year of exercise automatically triggers a disqualifying disposition. The spread at exercise flips to ordinary income. This can be a significant number for employees who exercised years ago at a low 409A price; the secondary price may be many multiples of that exercise price.
The AMT question for ISO holders who exercised early
Some employees exercised ISOs years ago — sometimes right after joining, sometimes under an early exercise provision — specifically to start the holding period clock and limit AMT exposure to a time when the 409A valuation was low. If that is your situation, and the secondary sale happens after you have held the shares for more than one year post-exercise and more than two years post-grant, you are in qualifying disposition territory. Your gain is long-term capital gain. The AMT credit you may have accumulated from the exercise year can potentially offset regular tax owed in the sale year.
If you exercised ISOs more recently — within the past year — and are now considering a secondary sale, you face a choice. Sell now as a disqualifying disposition and pay ordinary income rates on the spread, but potentially avoid AMT risk if the stock declines before an IPO. Or wait until the one-year anniversary of exercise, achieve qualifying treatment, and pay long-term capital gain rates, but remain exposed to price movement in the interim.
That is a tax and risk planning question your accountant needs to model with actual numbers. General articles, including this one, cannot tell you which path is better for your situation.
Practical steps before listing your shares
Before you engage a marketplace, pull your option grant agreement and confirm whether each grant is labeled NSO or ISO. Companies frequently grant both types, sometimes in the same equity plan — ISOs to employees up to the annual ISO cap under the tax code, NSOs for amounts above that cap or to consultants and advisors who do not qualify for ISO treatment.
- Locate your grant notices in your equity management platform (Carta, Pulley, or the company's cap table tool).
- Confirm the grant type — NSO or ISO — for each individual grant.
- Record the grant date and exercise date for any shares already exercised.
- Calculate the spread: current secondary bid price minus your exercise price. This is your preliminary gross gain.
- Identify whether you have met qualifying disposition holding periods for any exercised ISOs.
- Ask your tax advisor to model the after-tax proceeds under each scenario: qualify, disqualify, or wait.
- Confirm with your equity plan administrator whether a secondary transfer requires the company to process an exercise on your behalf and what payroll withholding will be triggered.
How secondary pricing interacts with your basis
Secondary markets price shares, not options. If you hold unexercised options, the marketplace will help you determine an implied share price and then back-calculate what net proceeds look like after exercise costs and tax withholding. The secondary sale price you see quoted is not your take-home number — it is a gross price per share before exercise, taxes, and any transaction fees.
The gap between the quoted secondary price and your net proceeds can be large. An NSO holder selling at a significant premium to the 409A price will recognize a spread at exercise as ordinary income, potentially at the top marginal federal rate plus state income tax, plus payroll taxes. For an ISO holder in a disqualifying disposition, the economics are similar. Modeling this carefully — before you sign anything — is the only way to know whether the sale achieves your liquidity goals.
At Limen Markets, sellers using our platform receive a net proceeds model as part of the onboarding process. We walk through the components — exercise price, spread, estimated withholding, transaction costs — so that the number you are negotiating toward is a realistic after-tax figure, not a headline price that disappoints at settlement.
One structural note on ROFR and exercise timing
Many private companies require that shares be exercised and held — not merely optioned — before the ROFR process can begin. This means you may need to fund an exercise out of pocket, hold the shares during the ROFR window (typically 15 to 30 days), and only receive secondary sale proceeds at settlement. If you exercise ISOs to initiate this process, the clock on your qualifying holding period starts ticking from the exercise date, not from the date you listed the shares. If you close the secondary sale before the one-year anniversary, you will have a disqualifying disposition regardless of how long the process took.
Plan the exercise date with the settlement timeline in mind. A transaction that takes 45 days from exercise to settlement clears the ROFR window comfortably but still does not satisfy the one-year ISO holding requirement. If qualifying treatment matters to you, exercise needs to have happened well before the secondary listing begins.
If you are ready to understand what a secondary sale of your specific position would look like in net terms, visit the seller section to start the process. Bring your grant documentation and a rough sense of your current tax situation — the net proceeds model is most useful when it is built around real numbers.