[mi100hael]

Typically exercising options gets taxed as regular income on the difference between option strike price & fair market value.

If OP had something like $300k of options, that'd be about a $100k tax bill assuming the strike price was appropriately low. Not a very big payout on a 9-figure exit, but also not pocket change for the taxes.

[deanmoriarty]

Well, if the "9 figure" was 100M, then 300k seems fair, since after 10 years of fundraisings and even minor dilutions, it's very easy and expected to go from 1% to 0.3%.

On the other hand, if the amount was 500M, 300k seems very low, hinting to a final ownership of ~0.06%. If that was true, even after considering all dilutions, that makes me think that OP didn't negotiate a fair equity package to begin with, since as employee #1 you should definitely have at least 1%.