Abstract
This paper not only provides a comparison of recent models in the valuation of mortgage-backed securities but also proposes an integrated model that addresses important issues of path-dependence, exogenous prepayment, transaction costs, mortgagors’ heterogeneity, and the housing devaluation effect.
Recent research can be categorized into two frameworks: empirical and theoretical option pricing. Purely empirically derived models often consider estimation of the prepayment model and pricing of the mortgage-backed security as distinct problems, and thus preclude explanation and prediction for the price behavior of the security. Some earlier theoretical models regard mortgage-backed securities as default-free callable bonds, prohibiting the mortgagors from exercising the default (put) option, and therefore induce bias on the pricing of mortgage-backed securities. Other earlier models assume homogeneity of mortgagors and consequently fail to address important issues of premium burnout effect and the path-dependence problem.
The model proposed is a two-factor model in which the housing price process is incorporated to account for the effect of mortgagor’s default and to capture the impact of housing devaluation. Default is correctly modeled in terms of its actual payoff through a guarantee to the investors of the security such that the discrepancy is eliminated by assuming mortgage securities as either default-free or unin-sured. Housing prices have been rising at unsustainable rates nation wide, especially along the coasts, suggesting a possible substantial weakening in house appreciation at some point in the future. The effect of housing devaluation is specifically modeled by considering the possibility that the mortgagor might be restrained from prepayment even if interest rates make it advantageous to refinance.
Mortgagors’ heterogeneity and the separation of exogenous and endogenous prepayments are explicitly handled in the model. Heterogeneity is incorporated by introducing heterogeneous refinancing transaction costs. The inclusion of heterogeneous transaction costs not only captures premium burnout effect but also solves the path-dependence problem. Finally, the model separates exogenous prepayment from endogenous prepayment, and estimates their distinct magnitudes from observed prepayment data. This construction provides a better understanding for these two important components of prepayment behavior. The generalized method of moments is proposed and can be employed to produce appropriate parameter estimates.
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Bibliography
Becketti, S. and Morris, C.S. (1990). “The prepayment experience of FNMA mortgage backed securities.” Monograph Series in Finance and Economics, Saloman Center, New York University.
Black, F. and Scholes, M. (1973). “The pricing of options and corporate liabilities.” Journal of Political Economy, 81: 637–654.
Brennan, M. and Schwartz, E. (1978). “Finite difference methods and jump processes arising in the pricing of contingent claims: a synthesis.” Journal of Financial and Quantitative Analysis, 13: 461–474.
Brennan, M. and Schwartz, E. (1985). “Determinants of GNMA mortgage prices.” AREUEA Journal, 13: 209–228.
Buser, S.A. and Hendershott, P.H. (1983). “Pricing default-free fixed-rate mortgages.” Housing Finance Review, 3: 405–429.
Cox, J.C., Ingersoll, J.E. Jr., and Ross, S.A. (1985a). “An intertemporal general equilibrium model of asset prices.” Econometrica, 53: 363–384.
Cox, J.C., Ingersoll, J.E. Jr., and Ross, S.A. (1985b). “A theory of the term structure of interest rates.” Econometrica, 53: 385–407.
Cunningham, D. and Hendershott, P.H. (1984). “Pricing FHA mortgage default insurance.” Housing Finance Review, 13: 373–392.
Davidson, A.S., Herskovitz, M.D., and Van Drunen, L.D. (1988). “The refinancing threshold pricing model: an economic approach to valuing MBS.” Journal of Real Estate Finance and Economics, 1:117–130.
Dunn, K.B. and McConnell, J.J. (1981a). “Valuation of GNMA mortgage-backed securities.” Journal of Finance, 36: 599–616.
Dunn, K.B. and McConnell, J.J. (1981b). “A comparison of alternative models of pricing GNMA mortgage backed securities.” Journal of Finance, 36: 471–483.
Dunn, K.B. and Spatt, C.S. (1986). “The effect of refinancing costs and market imperfections on the optimal call strategy and pricing of debt contracts.” Working Paper, Carnegie-Mellon University.
Epperson, J., Kau, J., Keenan, D., and Muller, III W. (1985). “Pricing default risk in mortgages.” Journal of AREUEA, 13: 261, 272.
Hansen, L.P. (1982). “Large sample properties of generalized method of moments estimators.” Econometrica, 50: 1029–1054.
Hansen, L.P. and Singleton, K.J. (1982). “Generalized instrumental variables estimators of nonlinear rational expectations models.” Econometrica, 50: 1269–1286.
Hendershott, P. and Van Order, R. (1987). “Pricing mortgages: an interpretation of the models and results.” Journal of Financial Service Research, 1: 77–111.
Johnson, E.T. and Van Drunen, L.D. (1988). “Pricing mortgage pools with heterogeneous mortgagors: empirical evidence.” Working Paper, University of Utah.
Kau, J.B. and Kim, T. (1992). “Waiting to default: the value of delay.” Working Paper, University of Georgia.
Kau, J.B., Keenan, D.C., Muller, III W.J., and Epperson, J.F. (1992). “A generalized valuation model for fixed rate residential mortgages.” Journal of Money, Credit and Banking, 24: 279–299.
Kau, J.B., Keenan, D.C., and Kim, T. (1993). “Transaction costs, suboptimal termination, and default probabilities.” Working Paper, University of Georgia.
Kau, J.B., Keenan, D.C., Muller, III W.J., and Epperson, J.F. (1993). “The valuation at origination of fixed rate mortgages with default and prepayment,” forthcoming. The Journal of Real Estate Finance and Economics.
Lawless, J.F. (1982). Statistical Models and Methods for Lifetime Data. New York: John Wiley.
Merton, R. (1973). “Theory of rational optional pricing.” Bell Journal of Economics and Management Science, 4: 141–183.
Pearson, N.D. and Sun, T. (1989). “A test of the Cox, Ingersoll, Ross Model of the term structure of interest rates using the method of maximum likelihood.” Working Paper, Stanford University.
Richard, S.F. (1991). “Housing prices and prepayments for fixed-rate mortgage-backed Securities.” Journal of Fixed Income, 54–58.
Richard, S.F. and Roll, R. (1989). “Prepayments on fixed-rate mortgage-backed securities.” Journal of Portfolio Management, 15: 73–82.
Schwartz, E.S. and Torous, W.N. (1989). “Prepayment and the valuation of mortgage-backed securities.” Journal of Finance, 44: 375–392.
Stanton, R. (1990). “Rational prepayment and the valuation of mortgage-backed securities.” Working Paper, Stanford University.
Tauchen, G. (1986). “Statistical properties of generalized method of moments estimators of structural parameters obtained from financial market data.” Journal of Business and Economic Statistics, 4: 397–416.
Timmis, G.C. (1985). “Valuation of GNMA mortgage-backed securities with transaction costs, heterogeneous households, and endogenously generated prepayment rates.” Working Paper, Carnegie-Mellon University.
Titman, S. and Torous, W. (1989). “Valuing commercial mortgages: an empirical investigation of the contingent claims approach to pricing risky debt.” Journal of Finance, 44: 345–373.
Wang, W. (1994). “Valuation of mortgage-backed securities.” Working Paper, Columbia University.
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Hong, C.H.T., Wang, WC. (2006). MBS valuation and prepayments. In: Lee, CF., Lee, A.C. (eds) Encyclopedia of Finance. Springer, Boston, MA. https://doi.org/10.1007/978-0-387-26336-6_75
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DOI: https://doi.org/10.1007/978-0-387-26336-6_75
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