abstract:Option-adjusted spread (OAS) is the flat spread which has to be added to the Treasury yield curve in a pricing model (that accounts for embedded options) to discount a security payment to match its market price. OAS is hence model-dependent.
Now, it hasthreepricingmodesof the MBS: the method of establishing a pre-payment model, the method of the option-adjustedspreadand the method of the option pricing.