The wealth manager looked at the portfolio in November and gave straightforward advice: exercise some of the incentive stock options now to start the holding clock. If the shares were held for at least a year after exercise, the eventual gain would be taxed at long-term capital gains rates rather than ordinary income rates. Good strategy. Sound reasoning. The executive exercised 5,000 options.
The exercise price was $20 per share. The market price that day was $80. The spread was $300,000. None of that was sold. None of it was cash.
The CPA learned about the exercise in February. The AMT liability for that year exceeded $90,000.
What the concentration risk conversation usually covers
When a wealth manager raises concentration risk, they are talking about portfolio exposure. You have too much of your net worth in a single stock, usually your employer. If the stock declines, the damage is disproportionate. The right response is diversification: sell some, spread the proceeds, reduce the exposure.
This conversation is correct. A 40% allocation to a single stock is a risk. The wealth manager is right to flag it and plan around it.
What that conversation does not cover: the tax cost embedded in the unwinding plan, and whether the CPA has modeled it before the first share is sold or the first option is exercised.
How ISOs work at exercise
Incentive stock options are designed to defer regular income tax at exercise. When you exercise an ISO, you buy shares at the exercise price. If the market price is higher, you have a gain on paper. Under regular income tax rules, that paper gain is not taxable at exercise. It becomes taxable only when you sell the shares, and if you meet the holding periods, it qualifies for long-term capital gains rates.
The alternative minimum tax treats ISOs differently. For AMT purposes, the spread between the exercise price and the fair market value at exercise is an AMT preference item: income that triggers the AMT calculation in the year of exercise, regardless of whether the shares are sold.
In the scenario above: exercising 5,000 options with a $60 spread creates a $300,000 AMT preference item. The executive has no additional cash. They have shares that were worth $80 when they exercised and may be worth more or less tomorrow. But the AMT calculation happens in the year of exercise, and the resulting tax is due in April.
The wealth manager did not model this. Modeling it requires information the wealth manager doesn’t have: the executive’s total income for the year, their existing AMT credit carryforward, and their regular tax picture.
The exercise decision is a tax decision
The optimal number of ISOs to exercise in a given year is not a portfolio question. It is a tax question. The answer depends on how much ISO exercise can be absorbed in the current year without triggering AMT, or how much AMT is acceptable given the long-term benefit of locking in lower capital gains rates.
A CPA who knows the full income picture can model this before the exercise happens. They can calculate how many options can be exercised at the current spread without generating AMT, or how to phase the exercise over two or three calendar years to spread the AMT exposure. They can identify whether the executive has AMT credit carryforwards from prior years that would offset a portion of the current year’s liability.
None of that analysis is possible in February, after the exercise has already occurred.
The seam
The wealth manager sees the concentrated equity position. They see the planning opportunity in long-term capital gains treatment. They make an exercise recommendation based on portfolio logic.
The CPA sees the tax return. They see what happened, and they report it accurately. They did not see the exercise decision before it was made, and they were not asked to model the tax exposure before the wealth manager gave the advice.
Both professionals are doing their jobs. The problem is that the exercise of an ISO is simultaneously a portfolio decision and a tax decision, and the two calculations have to happen at the same time, by the same people, before the shares are purchased.
The concentration risk in the portfolio is visible to anyone who looks. The tax risk from unwinding it is only visible to someone who knows both the portfolio and the tax return.
