浅析利率调整对住房抵押贷款违约风险的影响

住房贷款利率的变化对房地产价格产生着巨大影响,房地产价格又是住房抵押贷款中重要因素,与住房抵押贷款风险密切相关。违约风险是住房低押贷款风险中最基本最主要的风险,也称信用风险。论文将从理论上分析利率政策调整对住宅抵押贷款违约风险的影响,并提出相应的防范措施。     

A Note on Mortgage Risk: Default vs. Loss Rates

This note reexamines the role of the loan-to-value ratio on mortgage risk. Whereas previous studies have focused on the default rate as a function of this term, this study considers the additional effect on the loss rate of defaulted loans. Because the dollar loss per amount originated is the product of the default rate and the loss rate on defaulted loans, the impact of the loan-to-value ratio on both the default and loss rates is crucial to explaining the impact of the loan-to-value ratio on mortgage risk. I find that both rates are significantly positively related to loan-to-value ratio and that the loss rate accounts for between 13% and 20% of total loan-to-value impact.     

Relocation Opportunities and Mortgage Default

This paper presents a theoretical model of residential mortgage default when borrowers face beneficial as well as costly relocation opportunities. It amplifies and extends previous work by providing explicit conditions leading to default. The model also establishes when a borrower's relocation decision and default decision are dependent and when they are not.
A central result is that there is a range of book equity wherein the decision to default is not determined solely by the current level of equity or the borrower's ability to continue the mortgage payments. Rather, various costs and benefits, both tangible and intangible, enter into the decision. Specific conditions are identified that lead to relocation without default, default and relocation, and no default or relocation. The effects of changes in the variables upon default probability are presented.
Assuming that the borrower does not wish to retain ownership in the property, the model also predicts whether an individual borrower will choose prepayment or default when a relocation is made. The choice depends on the value of the relocation opportunity faced by the borrower, as well as financial variables such as house value, mortgage balance, and transaction costs. This finding suggests that existing empirical analyses of default may have omitted explanatory variables.     

Mortgage Default in Local Markets

Using recent theoretical advances and an extensive panel data set on metropolitan areas, this study provides new tests of the contingent claims based model of default. The empirical modeling incorporates a full complement of variables that permit direct tests of the options-based model including the conditional effects of age and rent-to-price ratios. The role of transaction costs and trigger events is examined, and the results confirm the importance of both. The effects of aggregation and short sample periods are explored and demonstrated to affect inference in studies of mortgage default.     

Determinants of Multifamily Mortgage Default

Option–based models of mortgage default posit that the central measure of default risk is the loan–to–value (LTV) ratio. We argue, however, that an unrecognized problem with extending the basic option model to existing multifamily and commercial mortgages is that key variables in the option model are endogenous to the loan origination and property sale process. This endogeneity implies, among other things, that no empirical relationship may be observed between default and LTV. Since lenders may require lower LTVs in order to mitigate risk, mortgages with low and moderate LTVs may be as likely to default as those with high LTVs. Mindful of this risk endogeneity and its empirical implications, we examine the default experience of 495 fixed–rate multifamily mortgage loans securitized by the Resolution Trust Corporation (RTC) and the Federal Deposit Insurance Corporation (FDIC) during the period 1991–1996. The extensive nature of the data supports multivariate analysis of default incidence in a number of respects not possible in previous studies. Consistent with our expectations, we find that LTV evidences no relationship to default incidence, while the strongest predictors of default are property characteristics, including three–digit ZIP code location and initial cash flow as reflected in the debt coverage ratio. The latter results are particularly interesting in that they dominated the influence of postorigination changes in the local economy.     

Mortgage Lending, Sample Selection and Default

Traditional models of mortgage default suffer from sample-selection bias because they do not control for the loan approval process. This paper estimates a sample-selection-corrected default model using the 1990 Boston Federal Reserve loan application sample and the 1992 Federal Housing Authority (FHA) foreclosure sample. A single-equation FHA default model appears to suffer from substantial selection bias, but the bias primarily arises from the omission of credit history and other variables that are only in the application sample. Therefore, default models that contain detailed information on applicants may not suffer from substantial selection bias. Finally, a test for prejudice-based discrimination is developed and conducted, but the findings are inconclusive.     

The Conditional Probability of Mortgage Default

This research examines the implications of contingent-claims models for empirical research on default. We focus on the probability of default over a short horizon given the current state of the world, i.e. , the conditional probability of default, which more closely resembles the estimates of empirical models. We highlight the differences between the conditional and unconditional approaches and provide guidance for empirical research by illuminating situations where the expected sign reverses over the shorter horizon or where the functional form is highly nonlinear.     

The Demand and Supply of Mortgage Funds and Mortgage Loan Terms

The supply of and demand for residential mortgages has been the subject of much discussion in the literature. Many of these studies have used single equation, partial adjustment models with the price specified as the contract rate. In this study, two of the assumptions that underlie these previous studies are tested empirically. First, the proper specification of the price of mortgage funds is tested by using both the contract rate alone and all of the terms of the mortgage as the price. Second, the speed of adjustment in the mortgage market is examined by estimating the model in both the instantaneous adjustment and partial adjustment forms. Both of these tests are carried out using a simultaneous equation rather than a single equation model. The empirical results indicate that the contract rate along with the loan initiation fees, the loan-to-value ratio and the maturity is the better specification of price and that the partial adjustment model performs better than the instantaneous model in the mortgage market.     

Mortgage Default Risks and the 1971 San Fernando Earthquake

The paper is based on a study of mortgage default risks associated with natural disasters. These risks are faced by holders of mortgages when forced by default to acquire damaged properties. A sample of residential mortgage properties damaged in the 1971 San Fernando, California earthquake is studied. Some of the mortgagors defaulted while others did not. The paper identifies and analyzes those variables associated with default using discriminant and probit regression analysis. The study concentrates on earthquake exposures in California, but has implications for all major disasters.     

Commercial Mortgage Pricing with Unobservable Borrower Default Costs

This paper develops a pricing model for commercial real estate mortgage debt that recognizes the influence of default transaction costs on the borrower's default decision. These costs are heterogeneous across borrowers and largely un-observable to the lender/investor at the time of origination or loan purchase. A recognition of these unobservable costs can explain why borrower default decisions may differ from those predicted by "ruthless" mortgage-default pricing models. We address the determinants of default choice and timing by replacing sharp default boundaries found in the ruthless models with "fuzzy" boundaries that account for investor uncertainty with respect to evaluating borrower default decisions. To implement our model, we estimate probabilities of default as a junction of time and net equity in the property. Then, given that default occurs, loss severities are modeled based on expected property value recovery net of foreclosure costs and time until the asset is actually sold. Under reasonable parameter value choices, resulting Monte Carlo simulations produce numerical mortgage price estimates as well as component default frequency and severity levels that realistically reflect default premiums and loss levels observed in the marketplace.     

A Dynamic Double-Trigger Model of Multifamily Mortgage Default

This study advances the commercial mortgage literature by providing theory and methods for incorporating both equity and cash-flow considerations in default models. We use local market conditions to compute a (joint) probability that default is in-the-money, based on both equity and cash-flow considerations. Statistical analysis is performed using data on multifamily mortgages originated in the 1980s and early 1990s. Simulations based on statistical modeling show advantages of the probabilistic double-trigger approach over other measures of equity and cash flow.     

Regional Economic Stability and Mortgage Default Risk in the Netherlands

This paper investigates the relationship between regional economic diversification and stability, and residential mortgage default risk in the Netherlands. To describe and measure regional economic diversity and stability, methods from both the regional economics and the industrial economics literature are used. All measures are based on regional employment characteristics. Mortgage default rates were obtained from a database of the population of insured mortgage defaults in the Netherlands from 1983 through 1990. To test the relationship between the measures and mortgage default risk, cross sectional Seemingly Unrelated Regression was used. The paper concludes that the employed measures explain regional mortgage default rates to a significant extent, and that stability measures outperform diversity measures.     

Mortgage Prepayment and Default Decisions: A Poisson Regression Approach

This paper uses an extensive and geographically dispersed sample of single-family fixed rate mortgages to assess the prepayment and default behavior of individual homeowners. We make use of Poisson regression to efficiently estimate the parameters of a proportional hazards model for prepayment and default decisions. Poisson regression for grouped survival data has several advantages over partial likelihood methods. First, when dealing with time-dependent covar-iates, it is considerably more efficient in terms of computations. Second, it is possible to estimate full-hazard models which include, for example, functions of time as well as multiple time scales (i.e., age of the loan and calendar time), in a much more straightforward manner than partial likelihood methods for un-grouped data. Third, Poisson regression can be used to estimate non-proportional hazards models such as additive excess risk specifications. Taken together, our data and estimation methodology allow us to obtain a better understanding of the economic factors underlying prepayment and default decisions.     

Optimal Sharing of Interest‐Rate Risk in Mortgage Contracts: The Effects of Potential Prepayment and Default

Much of the literature on the economics of mortgage markets has studied the fixed vs. adjustable‐rate mortgage choice made by individual borrowers. However, to decide if the outcome of such a choice is efficient or approximately so, it is necessary to explore the question of optimal risk‐sharing in mortgage contracts. But because only a small literature has studied this question, more research is clearly warranted. The present article helps fill this gap by developing a simplified version of Arvan and Brueckner's model, using it to characterize optimal contracts in the absence of mortgage termination, and then exploring how termination via prepayment or default affects optimal risk‐sharing. The broad conclusion of the analysis is that potential mortgage termination makes higher risk exposure for borrowers optimal.     

Industrial Real Estate Mortgage Default Experience of the New York State Job Development Authority Second Loan Program: A Preliminary Investigation

This paper explores the loan loss experience of a public industrial lending authority, employing contemporaneous borrower net equity as a link to mortgage loan default. The relationship between default, net equity and bankruptcy is tested on a small longitudinal data set of loans using nonparametric statistics and a proportional hazard model. Results show that negative net equity and firm bankruptcy are strongly associated with default among the study population. Further, the borrowers studied did not exercise the put option promptly, suggesting potential benefits from monitoring net equity one year or more prior to default.     

Equity Dilution: An Alternative Perspective on Mortgage Default

Empirical research on mortgage default in the single-family market has focused on the value of the borrower's put option using house price indices to estimate contemporaneous loan-to-value ratio or the probability of negative equity. But since the borrower possesses the option to increase leverage by taking on additional debt secured by junior liens subsequent to loan origination (a phenomenon termed here equity dilution ), even a perfect house price adjustment cannot be expected to accurately measure changes in borrower equity over time. Since junior liens are generally unobservable to senior debt holders, proxies are required in empirical applications. This paper employs an independent estimate of junior lien probability developed from the 1998 Survey of Consumer Finances combined with loan level mortgage performance data to examine the role junior liens play in increasing default risk.     

The Inevitability of Marketwide Underpricing of Mortgage Default Risk

Lenders are frequently accused of mispricing the put option embedded in nonrecourse lending. Prior research shows one lender's incentives to underprice. Here, we identify the conditions for a marketwide underpricing equilibrium. We demonstrate that, in a market with many players, given sufficient time, a race to the bottom and marketwide mispricing are inevitable. Underpricing occurs because bank managers and shareholders exploit mispriced deposit insurance. We show that the probability of the underpricing equilibrium increases with time since the previous market crash and that the more volatile the underlying asset market, the more likely it is subject to underpricing.     

Strategic Mortgage Default: The Effect of Neighborhood Factors

This article studies strategic default—the willingness of a borrower to walk away from a mortgage when the value of the home falls below the unpaid principal balance despite an ability to pay. This study differs from the literature in two fundamental ways. First, we use unique data assets describing the household's equity position and capacity to carry the debt in addition to credit performance to identify strategic defaulters accurately. Second, we address externalities from local foreclosures and other strategic defaults and find that the incidence of strategic default is sensitive to the presence of other nearby strategic defaulters. These results have significant implications for foreclosure and loss mitigation policies employed by servicers and investors.     

Spatial Heterogeneity in Mortgage Terminations by Refinance, Sale and Default

This article investigates the impact of spatially correlated unobservable variables on the refinancing, selling and default decisions of mortgage borrowers. Virtually the entire mortgage literature acknowledges that borrower-specific characteristics, such as culture, education or access to information, play an important role in mortgage termination decisions. While we do not observe these variables directly, we note that borrowers of similar background tend to cluster together in neighborhoods. We estimate a competing risks hazard model with random effects using a three-stage maximum likelihood estimation approach. We utilize the space-varying coefficient method to modify the covariance structure according to the spatial distribution of the observations. Beyond a significant improvement of the model performance, this yields a number of insightful implications for mortgage termination behavior. For instance, borrowers of the affluent "West Side" of Los Angeles County both refinance and move at a higher rate than predicted by the standard maximum likelihood estimation method. At the same time, borrowers from some lower-valued neighborhoods tend to stay longer than expected with their mortgages and properties.     

Financial Literacy,Broker–Borrower Interaction and Mortgage Default

This article examines the relationship between broker–borrower interaction in the origination process and subsequent mortgage performance. I show that face‐to‐face interaction between a mortgage broker and borrower before the loan funds is associated with lower levels of ex post default. The relation between face‐to‐face broker–borrower interaction and mortgage performance holds only for borrowers that have characteristics associated with low levels of financial literacy. Specifically, face‐to‐face interaction is negatively related to default for minorities, borrowers located in areas with low levels of education, low‐income borrowers and borrowers with low FICO scores. My results suggest that face‐to‐face interaction between the mortgage broker and borrower may reduce problems associated with financial illiteracy.