Prepayment and the Valuation of Mortgage-Backed Securities

This paper puts forward a valuation framework for mortgage-backed securities. Rather than imposing an optimal, value-minimizing call condition, we assume that at each point in time there exists a probability of prepaying; this conditional probability depends upon the prevailing state of the economy. To implement our valuation procedure, we use maximum-likelihood techniques to estimate a prepayment function in light of recent aggregate GNMA prepayment experience. By integrating this empirical prepayment function into our valuation framework, we provide a complete model to value mortgage-backed securities.     

What Drives Default and Prepayment on Subprime Auto Loans?

This paper uses novel data on the performance of loan pools underlying asset-backed securities to estimate a competing risks model of default and prepayment on subprime automobile loans. We find that prepayment rates increase rapidly with loan age but are not affected by prevailing market interest rates. Default rates are much more sensitive to aggregate shocks than are prepayment rates. Increases in unemployment precede increases in default rates, suggesting that defaults on subprime automobile loans are driven largely by shocks to household liquidity. There are significant differences in the default and prepayment rates faced by different subprime lenders. Those lenders that charge the highest interest rates experience the highest default rates, but also experience somewhat lower prepayment rates. We conjecture that there is substantial heterogeneity among subprime borrowers, and that different lenders target different segments of the subprime market. Because of their higher default rates, loans that carry the highest interest rates do not appear to yield the highest expected returns.     

Call Options, Points, and Dominance Restrictions on Debt Contracts

We analyze the impact of a contract's length, callability, amortization, and original discount by arbitrage methods. Among instruments that are callable without penalty, longer instruments command a higher interest rate because the borrower possesses the option of repaying relatively more slowly. However, the rate on longer self-amortizing loans cannot be substantially larger than for shorter ones because the payments decrease with contract length. Bounds on the trade-off between points and rate for callable debt are characterized using the trade-off for noncallable debt and the property that the value of the prepayment option increases with the loan's interest rate.     

Commercial Mortgage-Backed Securities: Prepayment and Default

One of the major developments in real estate finance during the 1990s was the emergence of a viable market for commercial mortgage backed securities. The growth in this market has spurred greater interest in empirical and theoretical research on commercial mortgage default and prepayment. We employ a competing risks model to examine the default and prepayment behavior of commercial loans underlying CMBS deals. We find that changes in the yield curve have a direct impact on the probability of mortgage termination. Furthermore, we do not find any statistical relationship between LTV and prepayment or default.     

A Top-Down Approach for Asset-Backed Securities: A Consistent Way of Managing Prepayment, Default and Interest Rate Risks

We define a new approach to manage prepayment, default and interest rate risks simultaneously in some standard asset-backed securities structures. We propose a parsimonious top-down approach, by modeling directly the portfolio loss process and the amortization process. Both are correlated to interest rates. The methodology is specified for sequential- and pro-rata pay bonds (ABS, CMO, CDO of ABS), cash or synthetic. We prove analytical formulas to price all tranches, under and without the simplifying assumption that amortization occurs in the most senior tranche only. The model behavior is illustrated through the empirical analysis of an actual synthetic ABS trade.     

Mortgage Terminations and Pool Characteristics: Some Additional Evidence

The amount and timing of unscheduled principal amortization determines the ex-post yield to holders of mortgage-backed securities. In this paper, the relationship between pool characteristics and the early return of principal is addressed. Empirical results are based on actual terminations from June 1985 to June 1986 on a sample of all GNMA pools. The relative termination experience of pools with loan rates close to the refinancing rate faced by the underlying borrower is examined in detail. The impact of pool age and size is also considered. Unscheduled termination depends on the refinancing rate, as well as the specific characteristics of a pool.     

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.     

Market turbulence creates financing opportunity

The flight to high-quality assets resulting from Standard & Poor's downgrade of the U.S. government's credit rating has dropped the yield on U.S. Treasury securities as investors have sought refuge amid uncertain market conditions. Consequently, hospitals can now obtain mortgage insurance from the U.S. government to finance expansions and refinance their debt with GNMA securities at taxable interest rates that are often more favorable than tax-exempt bond fixed rates. Because GNMA certificates can be sold in a forward purchase transaction that locks in a fixed interest rate while avoiding payment of interest until construction funds are disbursed, they can help avoid the effects of negative arbitrage.     

Market Risk of Mortgage-Backed Securities with Consistent Measures

Due to the complex prepayment behavior, mortgage contracts and their derivatives are generally priced using Monte Carlo simulations. The typical approach used by the industry, which involves simulating interest rates under the risk-neutral measure and applying a physically measured prepayment function, is subject to the problem of internal inconsistency. This is the first paper that directly investigates the potential impact of this issue. Following the general equilibrium setting by Cox, Ingersoll and Ross, we incorporate the market risk price parameter to derive the physical interest rate process from an observed yield curve. This allows us to model mortgage values under the consistent physical measures of interest rates and prepayment functions. By analyzing a default-free Ginnie Mae MBS, we find that the mixed measures lead to slower prepayment rate estimates and overpriced mortgage securities by approximately 5%. Further, there can be substantial biases in the duration and convexity measures depending on market condition and the particular security of interest. The internal inconsistency also leads to biased predictions of both expected and stressed returns for different investment horizons. Depending on the particular security, the bias in expected and stressed returns can be either positive or negative. These biases in risk estimates can introduce misallocation of risk-based capital and/or failure in hedging the market risk of a mortgage-related portfolio.

SELECTIVE HEDGING OF BANK ASSETS WITH TREASURY BILL FUTURES CONTRACTS

The recent volatility of interest rates, the associated profit pressures imposed on banks, and the surge in the development of new contracts have stimulated a desire to understand and apply financial futures hedging to banking operations. This paper models interest rate futures contracts in a theory of bank behavior to illustrate the hedging of bank loans as well as government securities. The model predicts the hedge will be greater (1) the greater the expected rise in interest rates and (2) the greater the effect of disintermediation on bank deposits. A simulation of the financial futures trading strategy is reported for banks of various asset sizes using data from the Eleventh Federal Reserve District. Depending on bank risk aversion and interest rate expectations, hedging the bank's total interest rate exposure with T-bill futures reduces the variability of unhedged profits by 80 percent.     

Mortgage contract design and systemic risk immunization

This paper provides theoretical results for the design of contracts used in the market for residential household mortgages and mortgage securities. Critical elements in the problem of immunizing systemic risk through efficient contract design are identified. Using an extension of classical immunization theory, this paper demonstrates that systemic risk of long amortization mortgage contracts is reduced when term to maturity of the contract at origination is significantly less than the amortization period. In addition, incorporating prepayment and limited recourse default options into the mortgage contract increases systemic risk when compared with full recourse mortgage contracts having yield maintenance prepayment penalties. The theoretical results are used to evaluate the systemic risk management problems that have plagued the US mortgage funding system.     

The valuation at origination of fixed-rate mortgages with default and prepayment

This paper develops a model to rationally price fixed-rate mortgages, using the arbitrage principles of option pricing theory. The paper incorporates amortization, prepayment and default in valuing the mortgage. Having completely specified the model, numerical procedures value the different features of the mortgage contract under a variety of economic conditions. The necessity of having both the interest rate and the house price as explanatory variables, due to the interaction of default and prepayment, is demonstrated. The numerical solutions presented center around mortgage pricing at origination. Thus, variations in the equilibrium contract rate are examined for differing economic conditions and changes in the contract. Finally, by presenting a complete model, the paper yields insights for the existence of common institutional practices.     

Private information and incentives: Implications for mortgage contract terms and pricing

We examine the linkage in equilibrium among (1) contract design; (2) expected prepayment and default likelihoods; and (3) the pricing of mortgage contracts by focusing upon the effects of the borrower's private information at the time of contracting. We examine the implications of these perspectives upon the empirical analysis of prepayment behavior and use the framework to examine the predominance of long-term mortgage contracts in the United States. We consider examples that explore the trade-offs between fixed and adjustable rate instruments, assumable and due-on-sale loans, and contract interest rates and initial discounts (points).     

Anatomy of an ARM: The Interest-Rate Risk of Adjustable-Rate Mortgages

This article analyzes the dynamics of the commonly used indices for adjustable rate mortgages and systematically compares the effects of their time-series properties on the interest-rate sensitivity of adjustable-rate mortgages. Our ARM valuation methodology allows us simultaneously to capture the effects of index dynamics, discrete coupon adjustment, mortgage prepayment, and both lifetime and periodic caps and floors. We can, moreover, either calculate an optimal prepayment strategy for mortgage holders or use an empirical prepayment function. We find that the different dynamics of the major ARM indices lead to significant variation in the interest-rate sensitivities of loans based on different indices. We also find that changing assumptions about contract features, such as loan caps and coupon reset frequency, has a significant, and in some cases unexpected, impact on our results.     

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.     

THE STATE OF THE HOME EQUITY SECURITIES MARKET (AND HOW TO IMPROVE IT): REPORT FROM A RECENT CONFERENCE

In 1998, a year which saw the origination of a record volume of single-family mortgage loans, at least 12 of the top 20 home equity lenders experienced severe problems related to their business models, accounting practices, and access to the debt and equity markets. In march of 1999, Banc of America Securities (BAS) sponsored a conference to explore the causes of and possible solutions to these problems.
This article begins by tracing the industry's problems to lenders' inability to sell the subordinated and residual classes of home equity securities, and goes on to argue that the key to the regular distribution of these securities lies in enhancing the quality and depth of information that lenders provide investors about the underlying loans. The article discusses four proposals for improving lenders' disclosure—proposals that are designed to increase institutional investors' demand for home equity securities by helping them to assess the prepayment and credit risk associated with the securities.
Following the author's summary of the BAS proposals, the article concludes with selected comments on the future of the home equity securities markets by two panels of experts representing bond insurers and rating agencies.     

利率市场化与银行资产配置选择 —基于45家商业银行的面板数据分析

本文在对商业银行资产配置进行理论分析的基础上,构建利率市场化对商业银行 资产配置影响的实证模型,利用45家商业银行2003-2014年的面板数据进行实证检验,实证结 果表明：利率市场化对信贷资产的增长没有产生激励效应,商业银行并未在利率市场化进程中 加速信贷扩张;利率市场化对商业银行资产配置结构产生了显著影响,随着利率市场化程度的 加深,信贷资产和证券资产在总资产中的占比都增大;利率市场化对信贷资产内部配置结构也 产生了显著影响,促进零售信贷资产占比提升,而对公司信贷资产占比和前十大客户信贷资产 占比的影响为负,这验证了在利率市场化的推进过程中,商业银行将信贷资源向个人客户和中 小企业客户倾斜,利率市场化发挥了一定的积极效应。     

Securitization markets and central banking: An evaluation of the term asset-backed securities loan facility

In response to the near collapse of US securitization markets in 2008, the Federal Reserve created the Term Asset-Backed Securities Loan Facility, which offered non-recourse loans to finance investors’ purchases of certain highly rated asset-backed securities. We study the effects of this program and find that it lowered interest rate spreads for some categories of asset-backed securities but had little impact on the pricing of individual securities. These findings suggest that the program improved conditions in securitization markets but did not subsidize individual securities. We also find that the risk of loss to the US government was small.     

Research Note: Revisiting Fair Value Accounting––Measuring Commercial Banks' Liabilities

IAS 39, Financial Instruments: Recognition and Measurement (IASB, 2000), requires assets to be marked to fair value if held-for-trading, available-for-sale purposes, or if they are derivatives; held-to-maturity securities, originated loans and originated securities are measured at amortized cost, providing they are not held-for-trading. Financial liabilities are measured at amortized cost except those that are held-for-trading or derivatives. A proposed amendment would accommodate improved fair value measurement of financial instruments. Commercial banks are greatly affected by any accounting standard concerning the recognition and measurement of financial instruments, whether related to assets or liabilities. This article demonstrates that the existing and proposed standards perpetuate the mismeasurement of interest rate risk for commercial banks. Under IAS 39 banks that have a balanced position, that is, no interest rate risk, counterfactually could show large changes in income through interest rate changes. An alternative accounting treatment, full fair value reporting of financial assets and liabilities, including all loans and deposits, is offered. Presently fair value data are mandated as footnote disclosure.