Walter Investment Management is taking steps to grow from a regional subprime servicer to a nationwide alternative to larger servicers. The real-estate investment trust recently closed a private placement of $135 million in residential mortgage backed notes and acquired Marix Servicing. The privately placed securitization consisted of mortgages originated nearly three years ago with a weighted average credit score of 575 and a weighted-average current loan-to-value ratio of 89.4 percent. Charles Cauthen, president and COO of