The recent rapid rise in interest rates has some market participants talking about margin calls on MBS investors, but so far all the chatter appears to be speculative – although there still could be red ink out there, somewhere. At press time, the yield on the benchmark 10-year Treasury had stabilized at 2.54 percent. In mid-May the rate was 1.70 percent. That’s a run-up of 84 basis points. One secondary market official told...