An investor in Alt A MBS originally issued by Residential Capital Corp. filed suit this week to block Nationstar Mortgage from auctioning nonperforming loans from the MBS pools. Nationstar in mid February began auctioning NPLs on auction.com, according to the complaint filed in the Supreme Court of New York State this week. There are currently two additional auctions totaling some $750 million of NPLs listed on the internet auction site, both believed to be related to Nationstar. The company is...