1. A computer readable medium having instructions stored thereon which, when executed by a processor, cause the processor to estimate a loss surface of a portfolio by: extracting an independent identically distributed series of loss innovations from a history of daily losses; estimating a semiparametric model of the loss innovations; determining one or more loss distribution functions F t T for a horizon of T days, when T≧1, based on the semiparametric model using a Fourier transform; and scaling the one or more loss distribution functions F T t by an estimate of current volatility.