With interest rates rising again, the future looks somewhat cloudy for real estate investment trusts that invest in MBS, a situation that investors have grown accustomed to the past few years. According to figures compiled by Keefe, Bruyette & Woods, the 28 mortgage investing REITs tracked by the firm had a combined market capitalization rate of $47.8 billion at the end of May, a slight drop from a year ago when the tally was $49.0 billion. Then again, not all of the 28 are...