Preliminary data suggest that mortgage securitization volume slipped to its lowest level of the year during May, as new issuance was down in virtually every corner of the market. A total of $147.71 billion of mortgage securities were issued during May, a decline of 6.8 percent from the previous month. Production reached its peak for the year in March, when a total of $178.78 billion of new MBS were brought to market. … [Two data tables included]