0.001% is still probably a generous estimate -- given Facebook's 3000 or so employees and the fact that all not-very-senior employees should add up to 2%.

Also, stock options need to have a hardly-discounted exercise price attached. That is, an employee that gets a stock option package reflecting shares worth $500K will have to shell out (at least) $450K to exercise them when the time comes. So based on this valuation, if facebook is worth "only" $70B in 4 years, the profit is going to be $250K or ~$60K/year. Nothing to sneeze at, and definitely a nice bonus -- but not more than that. And if facebook is worth $30B at the end of 4 years, today's stock option grant is worth virtually nothing.

My understanding is that all new hire grants @ facebook are given in restricted stock units (RSU) not options, in part to avoid the 500 shareholder rule.

I don't know how RSUs count against the 500 shareholder rule -- but for tax purposes, they count as an UNrestricted grant. That is, if you get $1M equivalent shares in RSUs, you get taxed immediately on that value, regardless of the restrictions. So you have to pay $350K (and that's just federal!), which you have no way to recover until the restriction is lifted. Worse, if you get fired the next day, you're out $350K with no way to reclaim them.

Pay attention to tax laws. If you are well off, that is your single largest expense.

I don't think I'm leaking any IP when I say that, if the stock grant were that generous, you probably would have heard about it.

edit: speaking, of course, of a newbie who was hired very recently with the 10 digit valuation in mind

I don't understand how you arrived at those percentages. Facebook already has 3k+ employees.

0.001% would be around ballpark.

$500k still isn't anything to sneeze at...

The options are granted at current fair market price, not 0.