MBS提前偿付的理论与方法及其比较

一、引言2005年底,中国建设银行发行了中国首单MBS——“建元2005-1个人住房抵押贷款支持证券”。MBS是住房抵押贷款支持证券的简称,它以住房抵押贷款这种信贷资产为基础,以借款人对贷款进行偿付所产生的现金流为收益来源与支撑,由金融机构发放的住房抵押贷款转化而成。金融机构通过在资本市场上出售这些证券给市场投资者,来达到融资的目的,并把对住房贷款借款人的所有权利转让给投资者,使住房贷款风险分散为由众多投资者承担。MBS最重要的特征就是它的可提前偿付性。所谓提前偿付,是指MBS的母体——住房抵押贷款可以随时被借款人提前偿付。由于MBS有回购条款,在沒有提前偿付惩罚条款下,借款人可以在贷款合同到期前选择提前偿付贷款余额。当提前偿付行为发生时,MBS的未来现金流是不确定的,从而使其到期收益率难以确定。要对MBS进行准确的定价,核心问题就是要对提前偿付行为进行有效的预测。而对于提前偿付行为的研究,大多是从影响因素和模型构建两个角度来进行的,下面分别就此进行比较研究。二、提前偿付的影响因素影响提前偿付行为的因素很多,但概括起来,可以分为利率因素和非利率因素两种。1.利率因素Dunn和McConnell从期权角度来研究...     

我国住房抵押贷款提前偿付风险的实证研究——基于宏观分析角度

提前偿付风险是住房抵押贷款证券化过程中所面临的主要风险之一,本文利用我国相关经济数据,从宏观角度建立计量经济学模型来测算各经济变量对提前偿付风险影响作用的大小。研究结果显示,我国居民收入水平的变化对住房贷款提前偿付的影响不显著,但房价变化率与住房抵押贷款利率的变化对提前偿付率均有显著影响。     

我国住房抵押贷款证券化提前偿付风险研究——以建元2007-1为例

住房抵押贷款证券化(MBS)是金融衍生工具之一。尽管MBS改善了银行资本结构并提高了资本市场流动性,但是和其他金融衍生工具一样,它也面临一定的风险。相较于违约风险和利率风险等,提前偿付风险成为住房抵押贷款证券化过程中的主要风险。本文探讨了MBS中存在的提前偿付风险,并以建元2007-1 MBS为研究对象,重点研究了其风险水平及影响因素。通过对建元2007-1 MBS数据的分析和建模,我们发现该产品的提前偿付率较高,这主要是由于经济环境、房地产价格、季节等因素的影响。为了防范提前偿付风险,本文建议加强信息披露、完善市场公开、建立专业化评级机构、完善MBS市场监管体系及配套制度、研究设立房贷事业部和相关政策性金融机构,以促进经济增长、刺激居民消费投资等。这些建议有助于降低提前偿付风险,确保MBS的稳健发展。     

我国住房抵押贷款提前偿付率的预测方法研究

一、引言 提前偿付是指借款人偿付的资金超过了每月计划偿付额,超出部分将未偿还的本金余额提前偿付.借款人的这种提前偿付行为,直接影响住房抵押支持证券的定价及其投资者的收益率,使银行面临再融资的风险,这一问题引起了学术界的极大关注.     

住房抵押贷款证券化的提前偿付风险分析

住房抵押贷款证券化是原始的抵押贷款形式从投资者与标的物之间的直接物权关系,转化为新的债务关系。具有优化金融机构的资产结构,提高住房抵押贷款的变现能力。住房抵押贷款证券化运行过程中存在很多风险,在住房抵押证券化的基础上,分析提前偿付风险的决定因素及相关模型,并对我国的提前偿付风险进行了简单的分析总结。目前我国已经开始对住房抵押贷款证券化1进行试点2,所以各种体系不完善,市场还不成熟,各种风险也疏于防范。这对于我国推进住房抵押贷款证券化的健康发展具有一定的理论指导意义。     

住房抵押贷款证券化的提前偿付风险分析

住房抵押贷款证券化是原始的抵押贷款形式从投资者与标的物之间的直接物权关系,转化为新的债务关系。具有优化金融机构的资产结构,提高住房抵押贷款的变现能力。住房抵押贷款证券化运行过程中存在很多风险,在住房抵押证券化的基础上,分析提前偿付风险的决定因素及相关模型,并对我国的提前偿付风险进行了简单的分析总结。目前我国已经开始对住房抵押贷款证券化1进行试点2,所以各种体系不完善,市场还不成熟,各种风险也疏于防范。这对于我国推进住房抵押贷款证券化的健康发展具有一定的理论指导意义。     

我国汽车消费贷款违约的实证分析——来自商业银行的微观证据

随着我国汽车消费信贷市场的发展,贷款违约问题越来越受到关注.本文将居民汽车消费贷款违约分为两类,利用银行消费贷款合约数据,运用Logit和Probit模型对影响汽车消费贷款违约的因素进行实证分析,揭示不同汽车价格区间内影响贷款违约的主要因素.研究结论是:对于购买普通汽车的借款人,贷款利率和借款人的收入负债比是导致违约的显著影响因素;对于购买豪华汽车的借款人,首付比例和汽车价格是导致违约的显著影响因素;违约率随汽车价格升高呈倒U型变化.     

住房抵押贷款证券化提前偿付风险的探讨

住房抵押贷款证券化应用中最为关键的一个环节就是对其进行合理定价,而定价就需要预测住房抵押贷款未来的现金流量,但抵押贷款人的提前偿付行为的存在影响着抵押贷款现金流量的确定。本文在定性描述了形成提前偿付行为的因素后,试图通过运用一些定量的分析来刻划提前偿付对住房抵押贷款证券定价的影响程度,以此对其提前偿付风险有更加清晰的认识。     

住房抵押贷款提前偿付的影响因素及风险防范研究

从宏观角度看,在众多影响因素中,利率、利率预期是导致我国借款人提前偿付的主要动因。本文运用线性回归模型定量分析利率、利率预期影响提前还款风险的显著性,并通过对显著因素的判断来有针对性地防范提前还款风险进行管理。     

新形势下个人贷款理性违约风险分析

一、个人贷款理性违约的概念违约风险是指银行在经营抵押贷款业务时面临的借款人因各种原因主动或被迫停止偿还部分或全部贷款的信贷风险。按借款人违约的主动性和被动性,可分为理性违约和被迫违约。所谓理性违约,即借款人觉得放弃继续还款可带来更大的利益时的违约行为。一般情况下,只有当房价出现下跌,特别是当跌幅超过借款人购房所支付全部费用时,借款人就容易选择停止继续支付贷款;另一种理性违约表现为提前还款,即当贷款利率下降时,借款人基于费用考虑选择提前偿还部分或全部贷款的情形,提前还款会增加银行成本,减少收益,但不会产生大的贷款风险。     

Time-Varying Mortgage Prepayment Penalties

Recent empirical findings reveal that prepayment decisions of commercial property owners are slower than predicted by the pure options-pricing model (OPM). Borrower decisions appearing slow, however, may be quite rational when prepayment penalties of a time-varying nature are incorporated into the OPM. This article uses a competing risks OPM, adjusted for each of four different categories of prepayment penalties, to analyze borrower prepayment behavior. We find the value of delaying prepayment is often higher for mortgages with declining-rate penalties than for mortgages with static-rate penalties, frequently requiring a substantially higher interest rate spread to trigger a refinance. Multifamily loan prepayment records reveal the type of prepayment pattern that the adjusted OPM indicate should occur, reducing the gap between empirical findings and theoretical predictions. The results have implications for the specification of regressions fit to historical data, for the pricing of newly originated commercial mortgages, and for pricing in the single-family market where prepayment penalties are reemerging.     

Frictions, Heterogeneity and Optimality in Mortgage Modeling

The purpose of this article is to provide a unified framework for incorporating frictions into a theoretical options-pricing model (OPM) for mortgages. This article presents formulation for a frictions-adjustable mortgage model that integrates borrower heterogeneity while simultaneously preserving prepayment and default financial decisions. Our model demonstrates the flexibility of the OPM by simulating separate and concurrent effects of three categories of frictions on the mortgage and mortgage components. Researchers can use our example formulation to determine the effects of specific borrower characteristics on mortgage values without destroying the options theoretic framework.     

A New Prepayment Model (with Default): An Occupation-time Derivative Approach

A new prepayment model is developed, which improves the modeling of the borrowers decision process by incorporating an occupation-time derivative in the valuation framework of a fixed-rate mortgage. This option-theoretic mortgage valuation model is based on stochastic house-price and interest-rate models, and requires a particularly subtle technique to incorporate a new type of occupation-time derivative, where the barrier (which activates the derivative) is in the value process and not the underlying process (as it is in standard occupation-time derivatives). This new model simulates a delay in prepayment by the borrower (beyond the time simple ruthless prepayment dictates), thus increasing the value of the mortgage to the lender, compared to the value gained using more basic models. This allows for a more advanced borrower decision process, where a rational exercise structure is retained in a modified form. Empirical evidence supports this theory, which should be beneficial for accurate mortgage-backed security pricing. The results in this paper explore thoroughly the effect on the mortgage value of a delay in prepayment by the borrower on the embedded options held and on the insurance component.

Microfoundations of a mortgage prepayment function

This article focuses on the following question: how much of an interest rate decline is needed to justify refinancing a typical home mortgage? Modern option pricing theory is used to answer the question; this theory indicates that the answer depends upon several factors, which include the volatility of interest rates and the expected holding period of the borrower. The analysis suggests that the commonly espoused “rule of thumb” refinance if the interest rate declines by 200 basis points — is a fair approximation to the more precisely derived differential for many households. We also construct the prepayment behavior of a pool of mortgages in which the expected holding periods of the borrowers in the pool vary. The prepayment behavior of this simulated pool is used to generate a series of empirically testable hypotheses regarding the likely shape of an actual prepayment function and its determinants. Finally, actual prepayment data are used to estimate a hazard function that explains prepayment behavior. We find that the estimated model understates prepayment behavior relative to that predicted by the simulation model, which suggests that the simple option pricing model is not adequate to explain aggregate prepayment behavior.     

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 Default with Asymmetric Information

This article analyzes mortgage-market equilibrium when borrower default costs are private information. By applying the approach of Rothschild and Stiglitz (1976), it is shown that asymmetric information regarding default costs distorts the contract choices available in the mortgage market, preventing safe borrowers (those with high default costs) from fully satisfying their demand for mortgage debt. Large loans are available for a substantial interest-rate premium, but only risky borrowers find this premium worth paying. The article builds on an empirical literature designed to test the ruthless-default principle from option-based models of mortgage pricing. That literature provides evidence against ruthless behavior, suggesting that default costs play an important role in borrower decisions. The article takes a further step by arguing that such costs are private information, which has important implications for market equilibrium.     

Omitted Mobility Characteristics and Property Market Dynamics: Application to Mortgage Termination

Property market dynamics depend on changes in long run equilibrium and on impediments to adjustment towards equilibrium. Mortgage termination due to mobility, default and refinancing provides a lens for evaluating property market adjustments. The borrower’s decision to move as an adjustment mechanism in the property market is associated with utility-maximizing decisions to either prepay or default on the mortgage. The optimal choice between these two termination events may depend on unobserved propensities related to change in income, job location, or family size, and substantial inertial forces including search costs, neighborhood change and attachment to an area. We propose a method for modeling variables determining the impact of mobility on mortgage terminations with imperfect household and loan level data. Since omitted variables contribute to moving decisions and therefore to mortgage prepayment and default decisions, utility functions for sale and default are correlated through these unobservable variables; thus, the IIA assumption of the widely used Multinomial Logit Model (MNL) is violated. Under such circumstances, econometric theory suggests that the Nested Logit Model (NMNL) is a better choice, which obviates the limitation of MNL by allowing correlation in unobserved factors across alternatives. Using loan level micro data, we find empirical evidence showing significant correlation between sale and default due to omitted borrower mobility characteristics. Our simulations find that NMNL out performs MNL in out-of-sample prediction. Improved predictions of moves and defaults are applicable to micro and macro analysis of the housing market system.     

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.     

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     

A Closed Form Formula for Valuing Mortgages

We develop a closed form formula for the value of a fixed-rate residential mortgage that includes the provision that the borrower can prepay at any time with no penalty. The value of the mortgage equals the expectation, under the risk neutral probability measure, of the future cash flows. We model future cash flows by estimating an empirical model of prepayment behavior. A second change of measure leads to a closed form expression for the expectation. The closed form values explain most of the time series variation in MBS prices. The closed form formula significantly shortens the time to calculate mortgage values and durations and can be a useful tool for portfolio management and hedging.