Thanks, Fred and Ira, for your replies.
Ira, I think that you, with the viewpoint of a veteran .org member, may be underestimating the number of loans that could be sold off within a year of origination, for two reasons. First, many lenders here have quit lending, so they will have relatively fewer newer loans than in a representative population. Second, we'd like to think that the lenders here who are still lending are doing a better job at it, and will make relatively fewer loans that will turn bad right away. For these reasons, most of the late loans that folks here would like to see go are well beyond a year past origination, but for the entire population of Prosper loans, I'd bet that somewhere between 5 and 10% of loans should be sold off within a year of origination (and that's 5-10% of all loans, which might be as much as 1/3 of all defaults). That's part WAG and part just eyeballing Fred's late loan curves, which seem to me to show that (at least prior to July 07), roughly 10% of loans were 1+ late within six months of origination, which puts them in the ballpark for a within-a-year-sale if the sales were happening quarterly.
As for my second paragraph, I should have included the word "could" and phrased the question as an expression of wishful thinking. It just seems wrong to wish for a loan to go bankrupt rather than to have it sell, doesn't it?