Issuers of jumbo mortgage-backed securities stuck with plain vanilla mortgages in 2015, according to a new analysis by Inside Nonconforming Markets. Meanwhile, a wide variety of lenders contributed to jumbo MBS last year, with only one bank accounting for an outsized share of contributions. First Republic Bank was the top originator of jumbo mortgages that were securitized in 2015, accounting for nearly 20 percent of all jumbo MBS issuance ... [Includes two data charts]