Despite softening involvement during the last quarter of 2012, most of the top real estate investment trust MBS investors had healthy increases in their portfolios over the last year, including six that showed triple-digit increases, mostly on the strength of an active first half of the year. According to a new analysis by Inside MBS & ABS, REIT MBS investors as a group increased their MBS holdings by 47.4 percent in 2012, to a total $357.45 billion, despite a collective shrinkage of 4.1 percent during the fourth quarter of the year. All but $7.49 billion were in agency MBS. The biggest year-over-year portfolio gains were seen...[Includes one data chart]