there are two different lists.
the high priority waitlist and then the dreaded hold list.
the high priority waitlist:
-unranked
-the people on this list get re-reviewed by the executive committee and they start picking who they feel are the best amongst the people on this list.
-the chances of getting accepted are much better than if you are on the hold list...but actual percentage...50% is a bit high...maybe 30-40% is what my friend in one of the adcoms said.
the hold list:
-unranked
-is the 2nd priority waitlist
-will not hear from UCLA until July at the earliest, meaning that you will only be taken off if everyone from the high priority waitlist is taken off the list.
-chances of getting of this list is very difficult and my friend on one of the adcoms said he has not seen or heard anyone taken off the list in recent years.