TIAC is Title Industry Assurance Corp and they are a risk retention group formed by ALTA.  You have to be a member of ALTA to be insured through them.  Many people do not like them because they are a risk retention group.  I think it has something to do with not backed by the federal insurance bureau or something that I don't wuite understand.
If you do a search for messages abou them, Robert explained it well once before a few months ago.