I see two potential problems with the secondary market. First, Prosper has recently decided to censor loan applications after funding, so secondary purchasers would not have the ability to review the borrower's info. Second, if I read the filing correctly, the loans for sale would be $200 or over. This would exclude many $50 "diversifiers" in the lending community.
I don't quite understand where the $500,000,000 underwriting fee comes into play here in their SEC filing. I imaging the big boys coming in with their tried and true actuary tables to snap up all the undervalued - "pennies on the dollar", "get me out of prosper" secondary sellers.
I also image "big credit" will have access to loan apps, whereas lender joe will not.