Residential Mortgage Lending and Borrower Risk: The Relationship Between Mortgage Spreads and Individual Characteristics

The mortgage banking environment in Hong Kong is quite different from that in the United States. For example, the secondary mortgage market and mortgage insurance only started after 1997. Using a large data set on mortgages, we examine empirically how mortgage rates in this market vary with various individual borrower, property, and loan characteristics. We find that mortgage rates in Hong Kong do vary with individual characteristics, which suggests credit sorting according to both prepayment risk and default risk, as a higher mortgage rate is found to be related to either higher collateral (a lower loan-to-value ratio) or slower prepayment. The empirical results suggest that lenders in Hong Kong can observe the risk type of individual borrowers to a certain extent and charge a corresponding mortgage spread. Overall, the evidence is consistent with the sorting-by-observed-risk paradigm as in Berger and Udell (1990).     

Mortgage Delivery to the Secondary Market when Interest Rates are Falling

A borrower whose loan is committed to the securitization process has the ability and incentive to switch lenders if market rates drop during the loan origination period, which creates significant exposure for primary lenders. A simple secondary market contract innovation we call a mortgage rate drop guarantee (MRDG) could shift this risk to the securitizers who represent portfolio investors. Our simulation results indicate this shifting would have improved the risk/return distribution faced by originators without damaging the risk/return position of securitizers during our 1977–2010 sample period. Assuming conservative loan lives and origination periods, and competitive lending markets, the risk reduction features of MRDGs could also have generated significant interest savings for borrowers.     

GSEs,Mortgage Rates,and the Long-Run Effects of Mortgage Securitization

Our paper compares mortgage securitization undertaken by government-sponsored enterprises (GSEs) with that undertaken by private firms, with an emphasis on how each type of mortgage securitization affects mortgage rates. We build a model illustrating that market structure, government sponsorship, and the characteristics of the mortgages securitized are all important determinants of mortgage rates. We find that GSEs generally—but not always—lower mortgage rates, particularly when the GSEs behave competitively, because the GSEs implicit government backing allows them to sell securities without the credit enhancements needed in the private sector. Using our simulation model, we demonstrate that when mortgages eligible for purchase by the GSEs have characteristics similar to other mortgages, the GSEs implicit government-backing generates differences in mortgage rates similar to those currently observed in the mortgage market (which range between zero and fifty basis points). However, if the mortgages purchased by GSEs are less costly to originate and securitize, and if the GSEs behave competitively, then the simulated spread in mortgage rates can be much larger than that observed in the data.     

Mortgage Default during the U.S. Mortgage Crisis

Which theory can quantitatively explain the rise in mortgage defaults during the U.S. mortgage crisis? This paper finds that the double‐trigger hypothesis, which attributes mortgage default to the joint occurrence of negative equity and a life event such as unemployment, is consistent with the evidence. By contrast, a traditional frictionless default model strongly overpredicts the increase in default rates. This paper provides microfoundations for double‐trigger behavior in a model where unemployment causes liquidity problems for the borrower. This framework implies that mortgage crises may be mitigated at a lower cost by bailing out borrowers instead of lenders.     

Borrower Self-Selection,Underwriting Costs,and Subprime Mortgage Credit Supply

In the U.S., households participate in two very different types of credit markets. Personal lending is characterized by continuous risk-based pricing in which lenders offer households a continuous distribution of borrowing possibilities based on estimates of their creditworthiness. This contrasts sharply with mortgage markets where lenders specialize in specific risk categories of borrowers and mortgage supply is stepwise linear. The contrast between continuous lending for personal loans and discrete lending by specialized lenders for mortgage credit has led to concerns regarding the efficiency and equity of mortgage lending. This paper sheds both theoretical and empirical light on the differences in the two credit markets. The theory section demonstrates why, in a perfectly competitive credit market where all lenders have the same underwriting technology, mortgage credit supply curves are stepwise linear and lenders specialize in prime or subprime lending. The empirical section then provides evidence that borrowers are being effectively sorted based on risk characteristics by the market.     

Credit History and the Performance of Prime and Nonprime Mortgages

Although nonprime lending has experienced steady or even explosive growth over the last decade very little is known about the performance characteristics of these mortgages. Using data from national secondary market institutions, this paper estimates a competing risks proportional hazard model, which includes unobserved heterogeneity. The analysis examines the performance of 30-year fixed rate owner occupied home purchase mortgages from February 1995 to the end of 1999 and compares nonprime and prime loan default and prepayment behavior. Nonprime loans are identified by mortgage interest rates that are substantially higher than the prevailing prime rate. Results indicate that nonprime mortgages differ significantly from prime mortgages: they have different risk characteristics at origination; they default at elevated levels; and they respond differently to the incentives to prepay and default. For instance, nonprime mortgages are less responsive to how much the option to call the mortgage or refinance is in the money and this effect is magnified for mortgages with low credit scores. Tests also reveal that default rates are less responsive to homeowner equity when credit scores are included in the specification.     

Subprime Borrowers: Mortgage Transitions and Outcomes

Public policy concerns increasingly have focused on subprime lending. Our research uses a survey of prime and subprime borrowers to address whether borrowers inappropriately are channeled to the subprime segment, if once having taken out a subprime mortgage borrowers are stuck in this market segment, and whether borrowers face higher costs by taking out subprime mortgages. We find that subprime borrowers are less knowledgeable about the mortgage process, are less likely to search for the best mortgage rates, and are less likely to be offered a choice among alternative mortgage terms and instruments—possibly making them more vulnerable to unfavorable mortgage outcomes. Our analysis of market segmentation confirms that typical mortgage underwriting criteria are most important in explaining whether borrowers obtain prime or subprime mortgages—higher credit risk borrowers are more likely to get a subprime loan. Our results further show that search behavior and other demographic factors including adverse life events, age, and Hispanic ethnicity contribute to explaining market segment, suggesting that borrowers may inappropriately receive subprime mortgages. While we find some persistence to market segment—borrowers are more likely to take out a subprime mortgage if their previous mortgage came from the subprime segment—we also find that market segment is not immutable. Analysis of the survey responses indicates that borrowers with subprime mortgages significantly are more dissatisfied with their mortgage outcomes. This is not surprising because subprime borrowers look worse across typical mortgage underwriting criteria. Consistent with policy concerns, however, despite holding constant these and other factors, taking out a mortgage in the subprime segment, by itself, appears to increase dissatisfaction with mortgage outcomes. We do not provide a definitive answer to the question of whether subprime lending, on balance, serves homebuyers well by providing access to mortgage credit to those otherwise constrained, or rather serves homebuyers poorly by inappropriately assigning them to a market where costs are high and the ability to transition to more attractive prime mortgages remains low. Our analysis, however, does provide some empirical support for concerns raised by critics of subprime lending, and for this reason justifies continued public policy debate and analysis.     

Value Creation through Securitization: Evidence from the CMBS Market

Despite recent volatility and constraints in secondary market funding, analysts have ascribed substantial value creation to the securitization of commercial mortgages. Such value creation likely emanates from liquidity enhancements, regulatory arbitrage, price discrimination and risk diversification by pooling and tranching, gains from specialization in origination, servicing, and holding of mortgages, and the like. Indeed, such value creation would be consistent with past accelerated growth in the mortgage- and asset-based securities markets and the sizable profits earned by secondary market intermediaries. In this paper, we estimate the pricing effects of commercial mortgage securitization. We do so by applying loan level data from 1992–2003 to compare the pricing of conduit and portfolio loans held in CMBS structures. In contrast to portfolio loans, which are held for investment by originating institutions, conduit loans are originated for the sole purpose of sale and securitization in the secondary market. If securitization creates value, it should be evidenced in the relative pricing of conduit loans sold into CMBS pools and in a lower cost of capital to loan originators. We estimate a reduced-form model, in which the interest rate spread between commercial mortgages and comparable-maturity treasury securities varies with loan characteristics, capital market conditions, and conduit loan status. Estimation results indicate that securitization of conduit loans leads to an 11 basis points reduction in commercial mortgage interest rates. We assess robustness of results via hazard model tests for omitted variables and originator-specific effects. We further estimate a simultaneous equations model that accounts for the potential endogeneity of mortgage loan terms to the mortgage-treasury rate spread. Results of that analysis suggest a larger 20 basis points reduction in loan pricing among conduit loans sold into CMBS structures.     

Differences in the Cost of Mortgage Credit Implications for Discrimination

This paper estimates the mortgage interest rate differences paid by Asian, Hispanic, and African–American borrowers to a national home mortgage lender in the years 1988–1989. Controlling for differences in market rates, rate lock protection, and borrower risk factors, conventional loan interest rates are almost perfectly race-neutral. The single deviation from race-neutrality is that when interest rates fall during the borrower's rate-lock period, only African–American borrowers are unable to capture a share of this decline. Government (FHA and VA) credit models show small premia paid by African–American borrowers of about $1.80 per month on average. In government lending, Hispanic borrowers alone are unable to capture rate declines occurring during the borrower's rate-lock period.     

Household Income, Termination Risk and Mortgage Pricing

The premium embedded in home mortgage loans to compensate investors for their exposure to prepayment risk is a significant component of the cost of home mortgage lending. Moreover, there is some reason to believe that prepayment risk may be lower for loans to lower-income housing borrowers, especially those that are first-time home owners. If so, investor recognition of this advantage should facilitate greater willingness to acquire portfolios of lower-income housing loans, and encourage more competitive pricing in this segment of the market. This study investigates the possibility of differential mortgage prepayment behavior between lower-income home owners and non-low income home owners. The investigation relies on samples of the American Housing Survey spanning ten years of experience from 1985 to 1995. We find no significant difference between the termination or refinancing behavior of non-low income and low-income households. This result is robust to a number of alternative specifications such as restricting the low-income test group to non-moving households and to first-time owners. The same conclusions are derived from both aggregate prepayment rates and from analysis of individual household prepayment behavior.