Systems, methods and computer program products stored on a computer readable medium or media are described for providing pricing of mortgage-backed securities and other financial instruments. Multiple cashflow paths resulting from different interest rate development scenarios are consolidated into a single cashflow path. A continuously compounded interest rate spread (“equivalent cc spread”) corresponding to the option adjusted spread prevailing at the market is determined, as is a relationship between the two. Reformulating computations of option adjusted spreads and prices using an equivalent cc spread and factoring out assumption changes approximates individual cashflow path and interest rate path calculations and allows use of consolidated cashflows calculations as a very good approximation. In some embodiments, the consolidated cashflow and the relationship between two spreads is employed to compute the value of the financial instrument, as a very good approximation, at a later time, so that the price reflects changes in the market yield curve and the option adjusted spread. For example, interest rate paths, cashflow paths, consolidated cashflow paths, discount factors and the equivalent cc spread are computed at market close, and only the consolidated cashflow paths, discount factors and the equivalent cc spread (and not the interest rate paths and cashflow paths) are stored for later on-demand use when the discount factors are adjusted to reflect the then current market environment.