Jason Brimhall discusses common table expressions:
Wait! Hold on two seconds there! Surely the semi-colon is an absolute requirement because we see it everywhere that it is a mandatory requirement.
The reality is that the semi-colon requirement is not really entirely accurate. If the CTE happens to be in the same batch, then the previous statement in the batch must be terminated by the semi-colon.
This post went down an unexpected path, and ended up being rather interesting. Read the whole thing.