Wall Street wasn’t surprised by Fitch’s placing 29 AAA and AA classes from 13 single-asset commercial mortgage-backed securities transactions on rating downgrade watch while a review of terrorism insurance coverage is under way. Fitch’s move on Monday followed last Friday’s action by Moody’s, which placed the Aaa through Aa3 ratings for 11 single-asset office building securitizations on ratings watch, along with the Aaa ratings