GSEs,Mortgage Rates,and Secondary Market Activities

Fannie Mae and Freddie Mac are government-sponsored enterprises (GSEs) that securitize mortgages and issue mortgage-backed securities (MBS). In addition, the GSEs are active participants in the secondary mortgage market on behalf of their own investment portfolios. Because these portfolios have grown quite large, portfolio purchases (in addition to MBS issuance) are often thought to be an important force in the mortgage market. Using monthly data from 1993 to 2005 we estimate a VAR model of the relationship between GSE secondary market activities and mortgage interest rate spreads. We find that GSE portfolio purchases have no significant effects on either primary or secondary mortgage rate spreads. Further, we examine GSE activities and mortgage rate spreads in the wake of the 1998 debt crisis, and find that GSE portfolio purchases did little to affect mortgage rates. This empirical finding is robust to alternative identification assumptions and to alternative model and variable specifications.      

Liquidity in a Market for Unique Assets: Specified Pool and To‐Be‐Announced Trading in the Mortgage‐Backed Securities Market

Agency mortgage‐backed securities (MBS) trade simultaneously in a market for specified pools (SPs) and in the to‐be‐announced (TBA) forward market. TBA trading creates liquidity by allowing thousands of different MBS to be traded in a handful of TBA contracts. SPs that are eligible to be traded as TBAs have significantly lower trading costs than other SPs. We present evidence that TBA eligibility, in addition to characteristics of TBA‐eligible SPs, lowers trading costs. We show that dealers hedge SP inventory with TBA trades, and they are more likely to prearrange trades in SPs that are difficult to hedge.     

Semi-analytical MBS Pricing

This paper presents a multi-factor valuation model for fixed-rate callable mortgage backed securities (MBS). The model yields semi-analytic solutions for the value of MBS in the sense that the MBS value is found by solving a system of ordinary differential equations. Instead of modelling the conditional prepayment rate (CPR), as is customary, the pool size is the primary modelling object. It is shown that the value of a single MBS payment due at time t _n can be found by computing two expectations of the pool size at time t _n–1 and t _n respectively. This is a general result independent of any interest rate model. However, if the pool size is specified in a way that makes the expectations solvable using transform methods, semi-analytic pricing formulas are achieved. The affine and quadratic pricing frameworks are combined to get flexible and sophisticated prepayment functions. We show that the model has no problem of generating negative convexity as the spot rate falls, and still be close to a similar non-callable bond when the spot rate rises.     

The refinancing threshold pricing model: An economic approach to valuing MBS

Investigation of MBS prepayment data indicates that mortgagors have different interest rate levels, or thresholds, at which they exercise their option to prepay their mortgage. In order to properly value an MBS with heterogeneous mortgagors, Merrill Lynch has developed the Refinancing Threshold Pricing Model (RTP). The RTP model focuses on the refinancing decision of the mortgagor when pricing the mortgage pool. The model divides each pool into groups of mortgagors who share similar refinancing costs. Using market data, the RTP model endogenously determines both the implied costs that mortgagors face, as well as the proportion of the MBS pool in each refinancing cost group. In addition to determining pool value, the RTP model also calculates MBS duration, dP/dY and convexity. Comparison between RTP model values and actual market data reveals a strong correlation. The RTP has a wide range of applications, including valuing 15-year and 30-year conventional MBS; pricing interest-only (IO)/principal-only (PO) derivative MBS; determining new versus seasoned MBS price spreads; and valuing specific MBS pools.The information set forth was obtained from sources we believe reliable, but we do not guarantee its accuracy. Neither the information, nor any opinion expressed constitutes a solicitation by us for the purchase or sale of any securities or commodities. Merrill Lynch, Pierce, Fenner & Smith, Inc. or its affiliates may have either a long or short position in, and may buy and sell for its own account or the accounts of others, these securities.     

Limits of Arbitrage: Theory and Evidence from the Mortgage-Backed Securities Market

“Limits of Arbitrage” theories hypothesize that the marginal investor in a particular asset market is a specialized arbitrageur rather than a diversified representative investor. We examine the mortgage‐backed securities (MBS) market in this light. We show that the risk of homeowner prepayment, which is a wash in the aggregate, is priced in the MBS market. The covariance of prepayment risk with aggregate wealth implies the wrong sign to match the observed prices of prepayment risk. The price of risk is better explained by a kernel based on MBS market‐wide specific risk, consistent with the specialized arbitrageur hypothesis.     

Derivative mortgage securities: An overview

Derivative mortgage securities have proliferated since planned amortization and floating rate CMO classes were introduced in late 1986. Other recently created derivative securities include reverse floaters and deep-discount bonds of CMOs, CMO residuals, and stripped and senior/subordinated passthroughs. These securities, which are derived from fixed-rate mortgages, were created to meet investor demands for maturity certainly, interest rate and prepayment hedging, and enhanced credit. The rapid growth of derivative securities reflects expansion of the investor base for fixed-rate mortgages. It also suggests that these mortgages will continue to be a viable housing finance instrument in a volatile interest rate environment. For the future, the increased creation of derivative securities will make the secondary mortgage market more efficient, facilitating the funding of fixed-rate mortgage originations.The substance of this paper was originally written in late 1987 and many of the specific data reflect that time period.     

Did the Federal Reserve's MBS purchase program lower mortgage rates?

On November 25, 2008, the Federal Reserve announced it would purchase mortgage-backed securities (MBS). This program affected mortgage rates through three channels: (1) improved market functioning in both primary and secondary mortgage markets, (2) clearer government backing for Fannie Mae and Freddie Mac, and (3) anticipation of portfolio rebalancing effects. We use empirical pricing models for MBS yields and for mortgage rates to measure relative importance of channels: The first two were important during the height of the financial crisis, but the effects of the third depended on market conditions. Overall, the program put significant downward pressure on mortgage rates.     

The Impact of the 2007 Liquidity Shock on Bank Jumbo Mortgage Lending

This paper explores the consequences of the collapse of the private‐label residential mortgage‐backed securities market in 2007 on banks’ originations of jumbo mortgages. We show that jumbo lending declined by more at banks that were more dependent on this market and were less well capitalized. In contrast, banks that had little dependence on this market and were well capitalized increased jumbo originations. These findings highlight how dependence on the secondary market may cause amplification of financial shocks, and the potential value of capital requirements that are higher during periods of economic growth in mitigating the amplification effects.     

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.     

Looking Beyond Credit Ratings: Factors Investors Consider In Pricing European Asset‐Backed Securities

In this paper, we empirically investigate what credit factors investors rely upon when pricing the spread at issue for European asset‐backed securities. More specifically, we investigate how credit factors affect new issuance spreads after taking into account credit rating. We do so by investigating primary market spreads for tranches of non‐mortgage‐related asset‐backed securities issued from 1999 to the year prior to the subprime mortgage crisis, 2007. We find that although credit ratings play a major role in determining spreads, investors appear to not rely exclusively on these ratings. Our findings strongly suggest that investors do not ignore other credit factors beyond the assigned credit rating.     

Optimal securitization with moral hazard

We consider the optimal design of mortgage-backed securities (MBS) in a dynamic setting in which a mortgage underwriter with limited liability can engage in costly hidden effort to screen borrowers and can sell loans to investors. We show that (i) the timing of payments to the underwriter is the key incentive mechanism, (ii) the maturity of the optimal contract can be short, and that (iii) bundling mortgages is efficient as it allows investors to learn about underwriter effort more quickly, an information enhancement effect. Finally, we demonstrate that the optimal contract can be closely approximated by the “first loss piece.”     

Characteristics of Mortgage Terminations: an Analysis of a Loan-Level Dataset

Understanding mortgage termination behavior is crucial for valuating mortgage-backed securities. Analyzing a unique loan-level dataset, this study examines the characteristics of mortgage prepayment and default behaviors in the Korean housing and housing finance markets. We also analyze mortgage termination behaviors across regions, loan purposes, and periods. The results suggest that the prepayment rate of fixed-rate mortgages (FRMs) and the ratio of adjustable-rate mortgages to FRMs can provide meaningful signals for the Korean household economy. Although the macro-prudential policies pertaining to the loan-to-value ratio (LTV) and debt-to-income ratio (DTI) are very effective, their effects can vary depending on the region or loan purpose. Furthermore, the DTI and credit score cannot always identify the default risks of mortgages not intended for housing purchases even though such mortgages are more vulnerable to macroeconomic changes. The observed changes in default behavior indicate that the government’s policies to promote fixed-rate loans have achieved a certain degree of success.     

Mortgage Loan Securitization and Relative Loan Performance

We compare the ex ante observable risk characteristics, the default performance, and the pricing of securitized mortgage loans to mortgage loans retained by the original lender. In our sample of loans originated between 2000 and 2007, we find that privately securitized fixed and adjustable-rate mortgages were riskier ex ante than lender-retained loans or loans securitized through the government sponsored agencies. We do not find any evidence of differential loan performance for privately securitized fixed-rate mortgages. We find evidence that privately securitized adjustable-rate mortgages performed worse than retained mortgages, although other observable factors appear to be more economically important determinants of mortgage default. We do not find any evidence of a compensating premium in the loan rates for privately securitized adjustable-rate mortgages.     

Pricing mortgages: An interpretation of the models and results

Mortgages, like all debt securities, can be viewed as risk-free assets plus or minus contingent claims that can be usefully viewed as options. The most important options are: prepayment, which is a call option giving the borrower the right to buy back the mortgage at par; and default, which is a put option giving the borrower the right to sell the house in exchange for the mortgage. This article reviews and interprets the large and growing body of literature that applies recent results of option pricing models to mortgages. We also provide a critique of the models and suggest directions for future research.The Ohio State University and the National Bureau of Economic ResearchThe Urban Institute University of California at Los Angeles     

Trustee reputation in securitization: When does it matter?

We consider the role of trustees–who are nominated to protect the interests of investors–in securitization pricing and whether investors rely on them to mitigate risks. In particular, we examine the effect of trustee reputation on initial yield spreads of European mortgage‐backed security (MBS) issuances between 1999 and the first half of 2007. We find that engaging reputable trustees led to lower spreads during the credit boom period prior to the 2007–2009 financial crisis. Our findings suggest that trustees’ reputation was considered by investors to be more important when risk assessment became more challenging.     

The Duration of an Adjustable-Rate Mortgage and the Impact of the Index

With the increasing use of adjustable-rate mortgages for asset/liability management, there exists the need to properly evaluate their price sensitivity to interest rate changes. This paper provides a foundation by deriving the duration of an adjustable-rate mortgage. The properties of this duration are unique and have some important differences from those of fixed-rate securities. One important characteristic of an adjustable-rate mortgage concerns the index used to adjust the mortgage rate. It was found that the index tended to be more important than the adjustment frequency in determining the duration of an adjustable-rate mortgage.     

Systematic mistakes in the mortgage market and lack of financial sophistication

Institutions often offer a menu of contracts to consumers in an attempt to create a separating equilibrium that reveals borrower types and provides better pricing. We test the effectiveness of a specific set of contracts in the mortgage market: mortgage points. Points allow borrowers to exchange an upfront amount for a decrease in the mortgage rate. We document that, on average, points takers lose about $700. Also, points takers are less financially savvy (less educated, older), and they make mistakes on other dimensions (e.g., inefficiently refinancing their mortgages). Overall, our results show that borrowers overestimate how long they will stay with the mortgage.     

Unintended Consequences of Risk Based Pricing: Racial Differences in Mortgage Costs

The following analysis focuses on the role that risk pricing has had in the allocation and access to mortgage funds, specifically how it results in cost differences by race. Using a sample of fixed-rate first lien mortgages, we control for the risk characteristics of borrowers and assets. We find that borrowers with comparable credit quality experience significantly higher costs for mortgages in neighborhoods with a high density of minority households. Further, when the pricing differential is controlled for in a model of mortgage default, there is no support for neighborhood price differences. This finding illustrates a potential inequity that results from efficient/risk pricing in mortgage underwriting.     

Analyses of Mortgage-Backed Securities Based on Unobservable Prepayment Cost Processes

We propose a prepayment model of mortgage based on a structural approach in order to analyze prepayment risk of mortgage-backed securities (MBS). We introduce a continuous process named prepayment cost process. Specifically, each mortgager's prepayment time is defined by the first time when her or his prepayment cost process falls below zero, but prepayment cost processes are supposed to be unobservable in the market. We also introduce a risk unique to each loan pool of mortgages, called a loan pool risk (LPR), and we regard LPR as a systematic risk other than interest rate. Using the model, we discuss the conditional distribution of prepayment times and a risk-neutral valuation of pass-through MBS. It is shown that each mortgager's conditional non-prepayment probability and the posterior distribution of LPR play quite important roles in our study.This research is partially supported by Grant-in-Aid for Young Scientists (B) No. 16710108 from the Ministry of Education, Culture, Sports, Science and Technology.