IMO none of this really matters when you're picking whether or not to join a company. As an outsider, if a down round happens while negotiating, you should mov

IMO none of this really matters when you're picking whether or not to join a company. As an outsider, if a down round happens while negotiating, you should move on. In virtually any case where a company has a down round, or fails to meet preferences in a sale, you want to leave anyway. Your stock being worthless is the least of your problems. The exception is if you're specifically part of a turnaround, in which case you'll have a newly negotiated package (unless you were a VERY early hire sitting on a bunch of still in the money options or something).