Servicers of jumbo mortgages posted significant increases to their portfolios in 2017, according to a new ranking by Inside Nonconforming Markets. Among a group of 30 servicers, the combined jumbo portfolio increased by 9.5 percent on an annual basis to $984.28 billion as of the end of 2017. The growth in jumbo servicing outpaced the increase in total mortgages outstanding. The total unpaid principal balance of outstanding residential mortgages ... [Includes one data chart]