汽车消费、住房抵押贷款违约特性及对策

本通过对比住房抵押贷款和汽车消费贷款的违约特性，得出在利率由央行统一规定的条件下，对住房抵押贷款和汽车消费贷款，实行同样的首付款政策是不合理的，这导致目前汽车消费贷款的违约率居高不下。对于住房抵押贷款，银行可以适当降低首付款，来提高本银行住房抵押贷款在市场的竞争力，对于汽车消费贷款，可以通过采取提高汽车贷款首付款的措施，来降低违约率，控制抵押贷款风险。     

Effects of risk aversion and decision preference on equilibriums in supply chain finance incorporating bank credit with credit guarantee

We constructed a Stackelberg game in a supply chain finance (SCF) system including a manufacturer, a capital‐constrained retailer, and a bank that provides loans on the basis of the manufacturer's credit guarantee. To emphasize the financial service providers' risks, we assumed that both the bank and the manufacturer are risk‐averse and formulated trade‐off objective functions for both of them as the convex combination of the expected profit and conditional value‐at‐risk. To explore the effects of the risk preferences and decision preferences on SCF equilibriums, we mathematically analyzed the optimal order quantities, wholesale prices, and interest rates under different risk preference scenarios and performed numerical analyses to quantify the effects. We found that incorporating bank credit with a credit guarantee can effectively balance the retailer's financing risk between the bank and the manufacturer through interest rate charging and wholesale pricing. Moreover, SCF equilibriums with risk aversion are highly affected by the degree of both the lender's and guarantor's risk tolerance in regard to the borrower's default probability and will be more conservative than those in the risk‐neutral cases that only maximize expected profit.     

基于区间数DEA的贷款定价模型研究

在贷款的买方市场或充分竞争的金融环境中,贷款利率不会由银行自己说了算,因此建立银企双方共同接受的贷款利率定价模型在现实中尤为重要。本文采用区间数的形式反映存款利息支出率、违约风险补偿率等定价指标的不确定性,以已结清贷款最小定价效率、最大定价效率组成的贷款定价效率区间为目标,以新贷款的贷款利率为决策变量,通过逆向求解区间数DEA模型反推出新贷款的贷款利率区间,建立了基于区间数DEA的贷款定价模型。本文的创新与特色一是以已结清贷款的存款利息支出率、目标利润率等指标为输入,以已结清贷款的贷款利率为输出,利用DEA模型求得已结清贷款的实际最小效率及最大效率。二是以银企双方均可接受的贷款定价效率区间为目标、以新贷款的存款利息支出率等用区间数形式表示的贷款成本为投入,反推出贷款利率的取值区间。三是通过区间数形式来反映违约风险补偿率、目标利润率等定价指标的不确定性,改变了现有研究将目标利润、贷款费用、违约损失等变量看作常数来定价的不合理现状。研究表明:存款利息支出率、费用支出率、违约风险补偿率及目标利润率均与贷款利率成正比。企业提高在贷款银行中的资金结算比率、存贷比率可以降低贷款利率。     

基于CAPM框架下的创业企业风险资本融资契约设计

从组合的视角出发,考虑创业企业家的风险厌恶程度,通过等价利率将创业企业的风险资本融资契约适应到CAPM框架下,利用纳什议价解刻画双方在信息不对称下的均衡解,基于风险-收益的角度建立了最优融资契约设计模型,为创业企业融资提供了契约设计和风险资本类型选择的一个依据,并通过算例说明了模型的可行性。研究还表明,创业企业引入风险资本优于纯债务融资,而股权的分配则取决于双方的议价力。同时,风险厌恶程度越低的创业企业家越趋向于选择独立的风险投资机构;风险厌恶程度越高的创业企业家越趋向于选择公司背景的风险投资机构;而风险厌恶程度不高,考虑后期贷款的创业企业家则趋向于选择银行背景的风险投资机构。     

基于不均衡数据的小企业信用风险评价

小企业信用风险评价既是银行风险管理问题,又事关经济社会稳定。针对小企业贷款实践中,违约样本远少于非违约样本、且违约客户误判对银行影响较大的现实,采用不均衡支持向量机对小企业信用风险评价指标进行赋权,进而构建了能有效区分违约客户、非违约客户的评价模型。根据有无特定评价指标、特定评价指标数值变化对贷款小企业违约状态的影响程度赋权;反映了对违约状态影响越大、评价指标权重越大的赋权思路。将违约样本正确识别率、违约样本的准确率与查全率等因素作为支持向量机赋权模型中客户识别率的度量标准,改变了样本数据不均衡所导致的样本总体精度很高、违约样本精度反而不高的现象。研究结果表明:行业景气指数、资本固定化比率、净利润现金含量、恩格尔系数、营业利润率等评价指标对小企业信用风险的影响较大。     

The role of index bonds in universal currency hedging

This study examines the demand for index bonds and their role in hedging risky asset returns against currency risks in a complete market where equity is not hedged against inflation risk. Avellaneda's uncertain volatility model with non-constant coefficients to describe equity price variation, forward price variation, index bond price variation and rate of inflation, together with Merton's intertemporal portfolio choice model, are utilized to enable an investor to choose an optimal portfolio consisting of equity, nominal bonds and index bonds when the rate of inflation is uncertain. A hedge ratio is universal if investors in different countries hedge against currency risk to the same extent. Three universal hedge ratios (UHRs) are defined with respect to the investor's total demand for index bonds, hedging risky asset returns (i.e. equity and nominal bonds) against currency risk, which are not held for hedging purposes. These UHRs are hedge positions in foreign index bond portfolios, stated as a fraction of the national market portfolio. At equilibrium all the three UHRs are comparable to Black's corrected equilibrium hedging ratio. The Cameron-Martin-Girsanov theorem is applied to show that the Radon-Nikodym derivative given under a P -martingale, the investor's exchange rate (product of the two currencies) is a martingale. Therefore the investors can agree on a common hedging strategy to trade exchange rate risk irrespective of investor nationality. This makes the choice of the measurement currency irrelevant and the hedge ratio universal without affecting their values.     

中国住房抵押贷款信用风险:理论分析与实证研究

住房抵押贷款为中国经济的持续增长增添了新的动力,随着规模扩大,其信用风险问题已经引起金融机构、政府部门及学者的关注.在分析中国房地产市场特点的基础上研究了适应中国住房抵押贷款违约的理论以及影响住房抵押贷款违约的因素,并通过采集大连市的数据进行了实证分析,首次运用实际数据来比选适应中国市场的理论模型.我们的研究发现:在中国住房抵押贷款市场上,贷款违约的还款能力理论较之于期权理论有着更好的适应性;利率、LTV、偿债比与户籍是影响住房抵押贷款违约的主要因素;也得出另外几个不同于理论假说的结论:家庭收入对借款人违约的影响力不明显,购买二手住房的借款人的违约概率要比新房高.     

金融租赁公司流动性风险研究

为研究金融租赁公司流动性风险,本文首次建立租赁公司现金流过程的多期动态模型,利用该模型定量分析了初始备付金、到期借款续借率和回收租金三个变量对公司流动性风险的影响。随后用违约概率来度量流动性风险,将问题转化成求解状态空间不断增大的非齐次马尔可夫链首中时的概率分布,并设计出违约算法(DA)和蒙特卡洛方法(MC)两种求解首中时分布的算法。算例表明提高初始备付金额度、到期借款续借率以及租金额度能有效地降低流动性风险。最后将银行的存贷利率和不同的租金定价方法融入基本模型,并通过三种不同的租金定价方式进一步分析了承租人信用风险对金融租赁公司流动性风险的影响。     

Mixture cure models in credit scoring: If and when borrowers default

Mixture cure models were originally proposed in medical statistics to model long-term survival of cancer patients in terms of two distinct subpopulations - those that are cured of the event of interest and will never relapse, along with those that are uncured and are susceptible to the event. In the present paper, we introduce mixture cure models to the area of credit scoring, where, similarly to the medical setting, a large proportion of the dataset may not experience the event of interest during the loan term, i.e. default. We estimate a mixture cure model predicting (time to) default on a UK personal loan portfolio, and compare its performance to the Cox proportional hazards method and standard logistic regression. Results for credit scoring at an account level and prediction of the number of defaults at a portfolio level are presented; model performance is evaluated through cross validation on discrimination and calibration measures. Discrimination performance for all three approaches was found to be high and competitive. Calibration performance for the survival approaches was found to be superior to logistic regression for intermediate time intervals and useful for fixed 12 month time horizon estimates, reinforcing the flexibility of survival analysis as both a risk ranking tool and for providing robust estimates of probability of default over time. Furthermore, the mixture cure model’s ability to distinguish between two subpopulations can offer additional insights by estimating the parameters that determine susceptibility to default in addition to parameters that influence time to default of a borrower.     

A Matched Asymptotic Expansions Approach to Continuity Corrections for Discretely Sampled Options. Part 1: Barrier Options

We propose a general framework to model equity volatility for a firm financed by equity and additional non-equity sources of funds. The stochastic nature of equity volatility is endogenous, and comes from the impact of a change in the value of the firm's assets on the financial leverage. We first present the basic model, which is an extension of the Black-Scholes model, to value corporate securities. Second, we show for the first time in the option literature, that instantaneous equity volatility is a solution of a partial differential equation similar to Black-Scholes', although it is non-linear and in general does not have any analytical solution. However, analytical approximations for equity volatility are proposed for different capital structures: (1) equity and debt, (2) equity and warrants, and (3) equity, debt and warrants. They are shown to be very accurate.     

风险规避型零售商资金约束下双渠道闭环供应链的定价决策

针对单一风险中性制造商和单一风险规避零售商组成的双渠道闭环供应链,建立制造商主导的Stackelberg博弈模型,讨论零售商分别通过银行贷款和延期支付解决资金约束问题时,各参与方的最优定价,分析回收率和零售商风险规避程度对决策结果的影响,并比较两种融资方式中决策结果的差异。研究表明:在双渠道闭环供应链中,零售商的资金约束不会影响批发价格、直销价格和零售价格随回收率的变化趋势。随着零售商风险规避程度的提高,银行贷款中批发价格的变化还与利率有关,直销价格始终降低;延期支付中批发价格始终提高,直销价格与之无关。当融资利率相等时,银行贷款中的批发价格始终高于延期支付,而直销价格和零售价格的相对大小还受利率和回收率的影响。     

基于混合模型的利润驱动违约判别临界点研究

违约判别临界点是金融机构是否接受客户贷款申请的重要参考,合适的违约判别临界点对减少金融机构贷款损失实现稳健经营具有重要意义。本文研究的问题是如何保证计算客户违约概率的准确性,并找到利润最大化的违约判别临界点。本文的创新与特色：一是通过将多个不同类型的违约判别模型计算的客户违约概率进行加权平均,保证了计算客户违约概率的的整体准确性,避免了使用单一模型计算客户违约概率不准确的弊端;二是通过定义金融机构从贷款中获得利润的计算公式,以利润最大为目标,求解违约判别临界点,避免了现有计算临界点的方法如广义对称点估计和经验似然法等方法得到的临界点利润不是最大的弊端。研究发现：混合模型比单一模型的准确性高,AUC值显著提高;在人人贷数据集中本文的违约判别临界点下贷款利润远高于其他方法下临界点的利润。     

我国新三板企业股权质押融资的风险评价

针对我国新三板市场的发展情况及新三板企业的自身特征,选择工业、信息技术和材料三个行业,采用PFM模型和VaR模型分别对新三板企业股权质押融资的违约风险和市场风险进行了实证分析.研究结果表明,PFM模型对于新三板企业违约风险度量具有较强的适用性,用VaR度量的股权质押融资的市场风险及其质押率与市场实际操作基本一致.从行业均值来看,新三板工业行业的违约风险和市场风险均为最小,信息技术行业的两者次之,材料行业则都最大.但是,进一步研究并未发现新三板企业股权质押融资的市场风险与违约风险存在显著的相关性.因此,股权质押融资风险主要来源于市场波动,企业经营状况对其没有直接影响.研究结果为新三板企业股权质押融资的风险防范提供了理论借鉴.     

Adverse selection and non-take inference with coherent risk and response scoring

The authors offer a mathematical model for adverse selection by individual borrowers based on preferences for offers and the default (Bad) or non-default (Good) status of booked accounts. We define the condition for borrower risk and response when there is no adverse selection (NAS). This definition provides us with a direct comparison between the prior and posterior conditional probabilities of default by an individual borrower who Takes an offer; this allows us to obtain estimates of differential response rates for individual borrowers and the Good/Bad odds for Take, Non-Take and Accept sub-populations. Performance of different response-risk segments allows us to compare price-driven risk elasticity and price-driven response elasticity in the presence of Good or Bad adverse selections; a special case applies when the borrower's capacity to repay is not an issue. We offer limited experimental results for selected price-risk segments where action-based risk and response scores are used to estimate borrower preferences. The critical role of Non-Take inference is described.     

The effects of asset liquidity on dynamic sell-out and bankruptcy decisions

We develop a dynamic bankruptcy model with asset illiquidity. In the model, a distressed firm chooses between sell-out and default, as well as its timing under the assumption that sell-out is feasible only at Poisson jump times, where the arrival rate of acquirers stands for asset liquidity. With lower asset liquidity, the firm increases the sell-out region to mitigate the risk of not finding an acquirer until bankruptcy. Despite the larger sell-out region, lower asset liquidity increases the default probability and decreases the equity, debt, and firm values. In the optimal capital structure, with lower asset liquidity, the firm reduces leverage, but the cautious capital structure does not fully offset the increased default risk. The stock price reaction caused by sell-out depends on the sell-out timing. When the firm’s asset value is not sufficiently high, the stock price jump size is an inverted U-shape with the economic state variable. Lower asset liquidity increases the jump size due to greater surprise. These results fit empirical observations.     

Pricing model of interest rate swap with a bilateral default risk

Under the foundation of Duffie & Huang (1996) [7], this paper integrates the reduced form model and the structure model for a default risk measure, giving rise to a new pricing model of interest rate swap with a bilateral default risk. This model avoids the shortcomings of ignoring the dynamic movements of the firm’s assets of the reduced form model but adds only a little complexity and simplifies the pricing formula significantly when compared with Li (1998) [10]. With the help of the Crank-Nicholson difference method, we give the numerical solutions of the new model to study the default risk effects on the swap rate. We find that for a one year interest rate swap with the coupon paid per quarter, the variance of the default fixed rate payer decreases from 0.1 to 0.01 only causing about a 1.35%’s increase in the swap rate. This is consistent with previous results.     

Efficient frontier cutoff policies in credit portfolios

Historically, account acquisition in scored retail credit and loan portfolios has focused on risk management in the sense of minimizing default losses. We believe that acquisition policies should focus on a broader set of business measures that explicitly recognize tradeoffs between conflicting objectives of losses, volume and profit. Typical business challenges are: ‘How do I maximize portfolio profit while keeping acceptance rate (volume, size) at acceptable levels?’ ‘How do I maximize profit without incurring default losses above a given level?’ ‘How do I minimize the risk of large loss exposures for a given market share?’ In this paper we are not concerned with which combination of objectives are appropriate, but rather focus on the cutoff policies that allow us to capture a number of different portfolio objectives. When there are conflicting objectives we show that optimal policies yield meaningful tradeoffs and efficient frontiers and that optimal shadow prices allow us to develop risk-adjusted tradeoffs between profit and market share. Some of the graphical solutions that we obtain are simple to derive and easy to understand without explicit mathematical formulations but even simple constraints may require formal use of non-linear programming techniques. We concentrate on models and insights that yield decision strategies and cutoff policies rather than the techniques for developing good predictors.     

基于区间效率的贷款定价研究

以存款利息支出率、费用支出率、预期违约损失率、目标利润率等4个定价指标作为输入,以贷款利率作为输出,采用支持向量机回归算法建立基于区间效率的贷款定价模型.创新与特色一是通过区间数形式来反映预期违约损失率、目标利润率、费用支出率等,改变了现有研究将目标利润、贷款费用、违约损失等变量看作确定性数值来定价的现状.使贷款利率更具有竞争性.二是通过比较不同核函数、核参数下的训练样本的贷款效率区间与合理的贷款效率区间的匹配程度,确定贷款定价模型最优的核函数和核参数,进而建立了贷款定价模型.间接解决了在考虑贷款价格能否被银行、客户接受情况下贷款利率确定的问题.     

Combining systemic and non-systemic risk scores

This paper proposes a proportional odds model to combine systemic and non-systemic risk for prediction of default and prepay performance in cohorts of booked loan accounts. We assume that performance odds is proportional to two independent factors, one based on age-dependent systemic, possibly external, global disruptions to a cohort of individual accounts, the other on traditional non-systemic information odds based on demographic, behavioural and financial payment patterns of the individual accounts. A proportional odds model provides a natural formulation that can combine hazard rate predictions of baseline defaults, prepayments and active accounts with traditional non-systemic risk scores of individuals within the cohort. Theoretical comparisons with proportional hazard models are illustrated. Although our model is developed in terms of Good/Bad performance, it can include late payments, prepayments, defaults, as well as responses to offers and other classifications. We make 60-month default and prepay forecasts under two different systemic risk scenarios for a portfolio of Alt A mortgages with 24-month ‘teaser rates’ originated in 2004.     

The economy and loss given default: evidence from two UK retail lending data sets

Loss given default (LGD) models predict losses as a proportion of the outstanding loan, in the event a debtor goes into default. The literature on corporate sector LGD models suggests LGD is correlated to the economy and so changes in the economy could translate into different predictions of losses. In this work, the role of macroeconomic variables in loan-level retail LGD models is examined by testing the inclusion of macroeconomic variables in two different retail LGD models: a two-stage model for a residential mortgage loans data set and an ordinary least squares model for an unsecured personal loans data set. To improve loan-level predictions of LGD, indicators relating to the macroeconomy are considered with mixed results: the selected macroeconomic variable seemed able to improve the predictive performance of mortgage loan LGD estimates, but not for personal loan LGD. For mortgage loan LGD, interest rate was most beneficial but only predicted better during downturn periods, underestimating LGD during non-downturn periods. For personal loan LGD, only net lending growth is statistically significant but including this variable did not bring any improvement to R².