Bank and thrift holdings of first-lien mortgages increased by 3.6 percent in the third quarter of 2012 compared with the third quarter of 2011, according to a new ranking and analysis by Inside Nonconforming Markets. The growth, outpacing portfolio runoff and an overall decline in mortgage debt outstanding, is tied to non-agency mortgages as well as agency-eligible loans being retained by banks. Industry participants are divided on whether the first-lien holdings will ... [Includes one data chart]