Case study: what happens to ISOs in an acquisition or IPO
A liquidity event finally lets you sell, and that is exactly when ISO holders make their most expensive mistakes. The money showing up is not the same as the money you keep.
ISOs · Case studies
What happens to your ISOs when the company gets bought or goes public? It depends on whether the deal lets you sell and when, and that timing controls your entire tax bill. The liquidity event is the moment everyone waits for. It is also the moment the tax tail starts wagging the dog hardest, because suddenly the money is real and the clock is loud.
Here is a composite of two outcomes from the same kind of event, to show that the deal structure is not the variable that matters most. Your timing is.
Names and numbers are a composite to protect the real people. The pattern is real.
Two ways the event arrives
The company lists. Your shares become sellable, but often only after a lockup period that keeps you from selling for several months. During the lockup, the price moves and you cannot act. When it lifts, you finally choose: sell, or hold for the qualifying long-term rate.
A buyer purchases the company. Your shares may be cashed out, rolled into the buyer’s stock, or your options cancelled or accelerated, all depending on the deal terms. Sometimes you have a choice. Sometimes the deal makes it for you, and your careful holding-period plan ends the day the deal closes.
The key difference: in an IPO you usually keep control over the sell decision after the lockup. In an acquisition, the deal can force a sale on a date you did not pick, which can blow up a qualifying-disposition plan you were a few months from completing.
Rohan held for the rate and it worked
Rohan had exercised his ISOs a couple of years before the IPO and paid the AMT on the spread along the way. See the AMT trap. By the time the lockup lifted, he had cleared both holding periods.
He had already cleared the clocks
More than two years from grant, more than one year from exercise. His gain qualified for the long-term capital gains rate. The discipline happened years earlier.
He sold into the lockup expiration, not on day one
He had a plan for how much to sell and when, rather than reacting to the opening price. He took real chips off the table instead of riding the whole position out of hope.
The AMT he prepaid started coming back
Because he had paid AMT at exercise, he carried a minimum tax credit, and the sale-year basis difference helped it flow back. See the AMT trap.
Priya waited too long and the dog got wagged
Priya’s company was acquired. She was about four months short of clearing the one-year-from-exercise clock, and she was determined to hold for the qualifying rate.
The mistake that hid inside her tax plan
Priya turned down a sane partial sale because selling early meant a disqualifying disposition and the higher ordinary rate. Then the deal terms forced a cash-out before she cleared the clock anyway. She got the higher tax rate and the forced timing. Worse, she had ridden the full concentrated position the whole way to protect a tax break the deal took out of her hands. The market does not care that you were four months from the lower rate.
The lesson is not that holding is wrong. It is that holding a concentrated position through a liquidity event to chase a tax rate is a bet on two things you do not control: the price and the deal terms.
The pattern under both stories
The money that arrives is not the money you keep
A liquidity event shows you a big number. Between that number and your bank balance sits the tax treatment, the lockup, the deal terms, and whatever AMT you already paid. The holders who do well decided their sell plan before the event, sized it to cut concentration, and treated the qualifying rate as a bonus, not a hostage situation.
Should I sell at the IPO or hold for the long-term rate?
If you have already cleared both clocks, like Rohan, holding costs you no tax break and the decision is pure portfolio: how much single-stock risk do you want? If you have not cleared them, like Priya, you are weighing a higher tax rate against the risk of riding a concentrated, newly public stock through a lockup. Frame it as after-tax dollars now vs probability-weighted dollars later, not as a tax rate you must protect. See how ISOs are taxed.
Can the deal really cancel my options?
Acquisition terms vary widely. Options can be assumed, cashed out, accelerated, or cancelled, and vested and unvested grants can be treated differently. This depends on the deal terms and your plan, so check your grant agreement and the deal documents, because the structure decides whether your holding-period plan survives the close.
What this means for you
In an IPO you usually keep the sell decision after a lockup. In an acquisition the deal can make it for you. Either way, the holders who keep the most are the ones who planned the sale before the event, took chips off the table to cut concentration, and never let a tax rate hold a concentrated position hostage. The big number on the screen is not yours yet. Decide what you keep before the event arrives, not in the rush after it. If a liquidity event is on your horizon, that is the time to build the plan.
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