It's the ability to do board-sanctioned sales of stock to buyers. It's basically an equity follow-on sale to previous investors (or new investors if there's a round concurrently underway).
This is significant because private companies typically have clauses in their option agreements that you can only sell shares pre-IPO if the board approves. So, a company like Palantir structures things so that, before an IPO, you can only make money off your options if you're still working at the company. Oh yeah, and if you leave and want to exercise your options so they don't expire (so that you can have a nest egg that vests when they IPO), be prepared to pay AMT on the difference between the strike price and the current value.
This is significant because private companies typically have clauses in their option agreements that you can only sell shares pre-IPO if the board approves. So, a company like Palantir structures things so that, before an IPO, you can only make money off your options if you're still working at the company. Oh yeah, and if you leave and want to exercise your options so they don't expire (so that you can have a nest egg that vests when they IPO), be prepared to pay AMT on the difference between the strike price and the current value.
They call it "golden handcuffs" for a reason.