Delegated SP is still owned by the person who delegates it. You just loose the voting ability of that 500sp and it does effect the slider bar availability.

What I as talking about is people who bought shares with steem become owners of the account and if/when they pull out of the program down the road they will get the value of the share back. So if the current share value is 1.5 steem they will get more back then they put in.