Originations of jumbo mortgages along with retention of some conforming loans helped bank and thrift holdings of first liens grow in the first quarter of 2015, according to a new ranking and analysis by Inside Nonconforming Markets. Banks and thrifts held $1.78 trillion in first liens in portfolio at the end of the quarter, up 0.9 percent compared with the fourth quarter of 2014 and a 2.4 percent increase compared with the first quarter of last year. The portfolios ... [Includes one data chart]