I can contribute 10% gross salary for a 15% discount.

Personally I always sell the ESPP immediately (assuming we aren’t in a blackout period). The way I see it, that 10% is my salary, and I don’t want to mess around with it and possibly end up making less than what I would have made had I not been in the ESPP at all. Luckily the stock more than doubled from the purchase price so I made out like a bandit anyway.

My stock options, however, I hold on to. Since it’s money I never had to begin with I’m much more comfortable taking a risk with it.