The employee exercised his options shortly after an IPO, but before he could sell the shares. By the time he could sell the shares, the stock had fallen to the point that the proceeds from sale didn't cover his taxes due. It wasn't enough to drive them to the poor house, but it was the difference between making money and losing money.
Why would you exercise the options in this time window at all? What's the upside versus just sitting on them until the window opens up?
Why would you even be able to exercise the options in the trading blackout window? Doesn't that count as trading itself?
If both trades happened in the same calendar year, then wouldn't the capital loss from the sale wipe out the capital gain from the exercise, such that he only owed tax on the difference between the strike price and final sale price?
What am I missing from this picture?