Most of the top 30 servicers of jumbo mortgages increased their servicing portfolios during the third quarter, according to a new Inside Nonconforming Markets ranking. The volume of jumbo mortgages outstanding rose to an estimated $892.4 billion as of the end of September, up 1.7 percent from June and up 10.2 percent from a year ago. Wells Fargo remained the top jumbo servicer, with a $275.1 billion portfolio. That was up 1.1 percent compared to the second quarter ... [Includes one data chart]