Mortgage production volume increased modestly during the fourth quarter of 2012, thanks largely to continuing gains by a number of mid-sized lenders, according to a new Inside Mortgage Finance ranking and analysis. An estimated $495.0 billion in new single-family mortgages were originated during the final three months of 2012, up 2.1 percent from the previous quarter. Including a slightly revised estimate for the third quarter, total mortgage originations hit $1.835 trillion during 2012 – a solid 24.8 percent gain over the previous year. That made 2012 the second-strongest year since the housing market began to come unglued back in 2007. It’s no surprise that agency programs continued...[Includes two data charts]