Social Finance is originating $70 million per month in jumbo mortgages and is considering issuing a jumbo mortgage-backed security, according to industry participants that have met with officials at the marketplace lender. Adjustable-rate mortgages accounted for approximately 25.0 percent of jumbo originations in May, according to Black Knight Financial Services. The firm said the jumbo ARM share of originations has declined from 29.0 percent as recently as ... [Includes five briefs]