September 4th, 2006, 10:38 am
stripping the risk-neutral PDs out from the market CDS spreads is a better method relative to have them from corporate bond data, since especially 5Y CDS is very liquid in market so the PDs do not include the "liqudity risk".the procedure is mainly called "bootstrapping" and a model-dependent bootstrapping methodology would be:assume you have market CDS spreads with 1 3 5 7 10 Year maturities, the constant recovery rate, the yield curve for discount factors...assume you have a stepwise constant hazard rate, i,e, \lambda_1 if 0 < t < 1 Y, \lambda_2 if 1<t<3 Y....and so on. then get a simple CDS pricing formula and with a JT95 type credit risk model setting assume that PD(0,t)= 1- (exp(-\int_0^t \lambda(s)ds )) -> since we assume the intensity rate is constant,it is easy to find the \lambda which are making the value of the CDS=0 at valuation date with a numerical algorithm(i.e fzero(...) in Matlab).this is an iterative method, i.e. we use the 1Y CDS market spread to find lambda_1,using lambda_1 and 3Y CDS market spread we calculate lambda_2 and so on....