Small lenders have accounted for a growing share of contributions to non-agency jumbo mortgage-backed securities. Some deals have included more than 70 lenders, with most of the lenders contributing less than 5 percent of the volume of mortgages included in a security. While the lenders’ individual contributions to a particular jumbo MBS are small, they add up to significant market share, particularly when issuers don’t identify the lenders in prospectus documents filed with the Securities ... [Includes two data charts]