The main purpose of this article is to provide an approximate general pricing formula for CMS spread options that can handle the case of nonzero strike rates. A generalized lognormal distribution is used to approximate the distribution of the difference between. two CMS rates. Pricing models for CMS spread options with nonzero strike rates are then derived under the multifactor LIBOR market model and also shown to be analytically tractable for practical implementation. The models are shown to be robustly accurate in comparison with Monte Carlo simulation.
