The outstanding supply of single-family MBS declined 0.7 percent during the first quarter of 2015, according to a new Inside MBS & ABS market analysis. But that didn’t stop commercial banks from continuing to increase their holdings. Banks increased their aggregate MBS holdings by 3.1 percent from the fourth quarter, pushing their share of the MBS market to 22.9 percent. The only other investor group that managed to increase its stake was the credit union industry, which posted a 1.6 percent increase from the previous quarter. The Federal Reserve finally loosened...