Issuance of non-agency mortgage-backed securities with prime jumbo loans and expanded-credit mortgages flourished in the first quarter of 2018, according to a new ranking and analysis by Inside Nonconforming Markets. Combined, $6.28 billion of such securities was issued, more than double the activity in the first quarter of 2017 and up 24.6 percent from the fourth quarter of last year. Some $4.23 billion of prime jumbo MBS was issued during ... [Includes one data chart]