Nothing - and it leads you to an even more difficult place. Imagine a late stage startup that has raised, say, $40m. You leave and execute your shares. Now they

Nothing - and it leads you to an even more difficult place. Imagine a late stage startup that has raised, say, $40m. You leave and execute your shares. Now they do another raise, but the company situation has changed and the next round is a down round, or maybe it's an up round, but the money has a 2 or 3x liquidation preference on it. Ugly.