Moody’s Investors Service announced last week that it is reviewing $47.5 billion in outstanding non-agency mortgage-backed securities for possible rating action. In a change of pace, however, most of the securities are being reviewed for potential upgrades. A whopping 78.3 percent of the combined subprime, Alt A, option ARM and jumbo MBS in question could potentially be upgraded. “The upgrade reviews are due to significant improvement in collateral performance and/or faster-than-expected pay-down on ...