One difference between the way Prosper and Lending Club report income is that Prosper reports rebates and promotions as a top-line deduction from its gross revenue in order to get to net revenue, while Lending Club appears to report them as marketing expenses after net revenue is reported. It reported a $314K deduction for these costs. If we move these rebates and promotions costs from the deduction-from-revenue line and add it to expenses, then adjusted revenues were about $609K and adjusted expenses were $3.446M, so adjusted revenues were about 18% of adjusted expenses, roughly double the ratio obtained from the raw figures.
This still isn't very good compared to Lending Club. But it's a huge improvement over 3QQ2010, when Prosper's financial situation was truly dismal. Prosper reported a tiny income from rebates and promotions for 3Q2010 ($3.5K), so last year there was no need for adjustment. It reported $96K revenue and 2.50M expenses, a 4% ratio.