A stock release and a stock sale are two different things.  Sometimes they happen at the same time (usually referred to as a Same Day Sale).  Sometimes the release statement will conveniently say "Same Day Sale" on it somewhere.  When in doubt:  guessing, assuming, or asking random people on the Internet is not going to give you the answer. 🙂  Get documentation from the client.  If this was sold, there should be a 1099-B.  If it was not sold, it would have been delivered into an account somewhere.  The client should get statements for that account.

Edit: IRMN snuck in ahead of me!  I'm bouncing back and forth between tax forums and the monthly IRIS Teams meeting.