Access to mortgage, as measured by the Mortgage Credit Availability Index (MCAI), decreased in May.  The Mortgage Bankers Association said the MCAI pulled back 1.1 percent to 181.0. The index was benchmarked at 100 in March 2012 and a decline indicates tightening of credit standards. Two of the component indices also decreased while the other two moved higher.

"Credit availability slipped in May, primarily driven by investors consolidating their offerings for government insured loans," said Lynn Fisher, MBA's Vice President of Research and Economics. "These decreases were partially offset by continued expansion among jumbo loan programs. The Jumbo MCAI has increased in 13 of the last 15 months."

As Fisher noted, the Government MCAI saw the greatest decrease in availability over the month (down 1.9 percent), followed by the Conforming MCAI (down 0.3 percent). The Conventional MCAI (up 0.2 percent) and the Jumbo MCAI (up 0.8 percent) both increased from last month.

The Conforming and Jumbo indices have the same "base levels" as the Total MCAI (March 2012=100), while the Conventional and Government indices have adjusted "base levels" in March 2012. MBA calibrated the Conventional and Government indices to better represent where each index might fall in March 2012 (the "base period") relative to the Total=100 benchmark.