The two biggest U.S. P2P lenders, Prosper and Lending Club, started operations in 2005 and 2007, respectively. Over the past decade, their business has grown so that they now originate more than $10 billion in loans per year. The public information provided by Lending Club gives us an opportunity to judge how they are doing. At first, P2P lending returns appear remarkably high (adjusted for volatility), but growing evidence of adverse selection highlights how difficult it will be to sustain growth.

When we last wrote about P2P lending, we suggested that profitability might be a consequence of the booming economy (see here and here). We concluded that one would need to see performance in a recession before judging P2P’s long-run potential. That is, when you are making consumer loans, it is relatively easy to make money as the unemployment rate falls from 10% to 3.5%. However, profitability over the course of an entire business cycle, including periods when joblessness is rising, is an entirely different story.

Well, maybe there is no need to wait….