Commercial banks and savings institutions continued their buying spree in the MBS market during the fourth quarter of 2015, according to a new ranking and analysis by Inside MBS & ABS. Banks and thrifts held a record $1.644 trillion of residential MBS in their available-for-sale and held-to-maturity portfolios as of the end of last year. That was up 2.2 percent from the third quarter and represented a 6.8 percent gain over 12 months. All of the increase came...[Includes two data tables]