lendingclub secondary market loans are riskier

I started testing lendingclub secondary market loan buying about three months ago.  The result is worse than my primary market performance.  I thought about the reasons and lessons I learned could be summarized to a few points.

1. Loans in secondary market are aged loans.  Payment already made goes to the sellers to cover potential loss.  As a loan buyer, your chance of losing a large percentage amount up to 100% is higher comparing to primary loan holder.  The reason is because of the term structure of default rates - default rates are low at early age and increase dramatically in middle age and slowly decrease at later age close to maturity. The effect can be seem by comparing two models performance; one considers term structure, another doesn't.  Based on a few months data, the one takes term structure into account performs better.
2. Lendingclub's investor fee effect.  Lendingclub charges 1% of payment made every month.  In early ages, a large portion of the payment is interest payment while in later ages, a large portion is principal payment.  Investor fee is 1% regardless and thus secondary loan buyer receives less interest payment sometimes even less than principal amount after fee.  It is amazing to see some sellers list loans with prices that have negative yield even though the asking price is close to outstanding principle.
3. Incomplete information effect.  Seller has more information than my automated models.  I observed that people have ever requested adjustment of payment dates are more likely to default. Although I couldn't prove or disprove my claim due to lack of data I do see sellers listed such loans as soon as a request to adjustment were made. It also appears that rapid fico drop signals immediate delinquency vs slow gradual fico decrease; again, my observation without strong data support.
4. Competition.  Sometimes my automated buying request failed because someone else bought before me. 

More work need to be done!