含时变风险厌恶系数的异质信念模型及实证分析

根据前景理论的反射效应,在做市商调整机制下,对市场中的两类投资者(基本面分析者和趋势追随者)同时引入时变的风险厌恶系数,扩展了异质预期下风险厌恶固定不变的资产定价模型.通过蒙特卡洛模拟,对噪声项和根本确定性系统之间相互作用的分析得出,模型能产生真实的价格行为.最后的实证模拟,对比分析了本模型,原模型及上证指数的收益序列特性,发现本模型能更好的模拟中国股票市场的收益率特性.     

非对称信息证券交易的跨期动态博弈均衡解析

揭示了不对称信息条件下证券市场均衡的基本特征.Grossman和Stiglitz模型依据不知情交易者的弱理性,解析了证券交易的静态均衡状态.O'Hara模型增强了不知情交易者的理性,强调了市场均衡时的风险定价,但其命题的成立条件是相互矛盾的.认为不知情交易者信息收集和处理能力的提高会使决策更为理性,证券市场的均衡本质上是交易者的动态博弈均衡.依此思路,运用不完美信息的跨期动态博弈模型解析了非对称信息条件下证券交易者的精炼贝叶斯纳什均衡.结论显示出,市场失效的主要原因是交易者之间的信息分析能力不平衡,而不是信息不对称;市场流动性的决定因素不是信息不对称风险而是知情交易者与不知情交易者所研判的无风险收益率的差别.     

考虑投资者风险态度的随机模糊投资组合模型及实证

考虑投资者面临证券市场随机和模糊的双重不确定性,把证券收益率视为随机模糊变量。在前景理论下考虑投资者的风险态度,建立不同的随机模糊收益率、期望收益隶属度函数和目标权重,构建考虑投资者风险态度的随机模糊投资组合模型。采用实证方法把市场分为下降和上升两个阶段,研究不同风险态度投资者的投资组合差异及模型表现。结果表明:投资者的风险态度会影响投资组合的结构;考虑投资者风险态度的随机模糊投资组合模型,能够满足不同风险态度投资者对投资收益和风险的差异需求,且在实际投资决策中具有可行性。     

市场需求信息不对称下的保兑仓融资风险控制策略

信息不对称风险广泛存在于保兑仓融资过程当中,本文运用Stackelberg博弈模型刻画融资系统成员关系,运用动态规划优化分析方法求解对应博弈均衡策略。总结出需求信息不对称的三种表现形式:信息造假,信息优势及信息隐匿,分析各类信息不对称情形对融资系统所造成影响,并相应提出实现信息显示功能的契约甄别机制。研究表明:零售商可从信息不对称中获取巨大信息优势,但对其他成员造成损害,其中信息隐匿对生产商损害程度更高;二部定价机制可实现信息甄别,但生产商须为之付出信息租金,造成效率损失;而合理参数设定下的二部定价加回购机制有助于进一步改进融资系统及各成员收益,甚至达到次协调状态,最终实现融资成员收益的帕累托改进。本研究对于控制供应链融资中的信息风险、改善融资效率提供了理论依据及决策参考。     

异质信息、异质先验信念与均衡资产价格

在卖空限制下,将信息异质和先验信念异质纳入统一的分析框架,利用贝叶斯法则推导出两类异质性共同影响下的均衡资产价格模型,进一步分析表明,两类异质性均对资产价格产生影响,但对价格波动的影响不同,异质信息投资者的增多或者先验信念异质性程度的增强会加快资产价格的涨或跌,甚至会导致暴涨或暴跌,这与Miller等仅对单异质性影响进行研究不同,研究揭示了市场中多类异质性的具体影响机制.     

不对称信息下逆向供应链定价分析与对策

以博弈论为研究方法,对由零售商和制造商组成的逆向供应链的定价问题进行研究,通过分析在回收成本信息对称和信息不对称情况下逆向供应链中制造商和零售商的定价策略,得出了在信息不对称情况下,制造商承担更大的风险。因此制造商需要防范回收成本信息不对称带来的风险,文章进一步给出了制造商的信息甄别合同,通过合同制造商可以降低由回收成本信息不对称带来的风险。     

我国A股市场投资者情绪是定价因子吗?

以股票价格变化的强弱和方向反映投资者的心理预期,选取流通性指标作为股票交易强弱的指标,股票买卖行为的人气指标作为投资交易方向的指标,从交易强弱和交易方向两个角度构建了投资者情绪综合指标(简记为ISI).选取2006年1月至2017年6月沪市A股上市公司为样本,进行了ISI与股票收益的时间序列分析和截面效应分析.研究结果表明,投资者情绪综合指标提高了预期收益率但降低了本期收益率,预期收益率具有显著的正向风险溢价.ISI自身也具有显著的正向风险溢价,对股票市场超额收益具有很好的解释能力.投资者情绪指标是中国股市一个重要的资产定价因子.     

基于异质理念的动态组合选取模型

不同于传统的代表性经济人的动态投资组合选取模型,引入异质理念,考虑不同投资者的动态组合选取.由于投资者的乐观或悲观情绪直接影响了他对信息的评价,因此用随时间变化的参数体现投资者的情绪,随机组合收益分布是这个参数的函数,不同的投资者或者同一投资者在不同情绪下就有了自己独特的收益分布.通过对均值——方差目标函数的变形,给出了不同投资者对风险资产的最优投入、预期收益和方差的解析表达式,此三项不仅和投资者的风险厌恶度有关,而且和投资期长短有关、与投资者的情绪有关.在对香港恒生指数的实证分析显示,异质性严重影响投资者对风险资产的投入.     

制造商信息私有条件下的双渠道供应链定价决策

针对由风险规避型制造商拥有的直销渠道和风险规避型零售商拥有的传统零售渠道组成的双渠道供应链模型,首先研究制造商和零售商的风险规避信息为共同知识条件下,直销渠道和传统零售渠道的定价决策。进一步分析制造商风险规避度为私有信息条件下,制造商和零售商的最优定价策略,探讨精炼贝叶斯均衡定价的存在条件。研究表明,信息非对称条件下,零售商即使存在信念的修正,其零售渠道的定价与制造商的定价决策类型始终保持一致,而制造商的最终定价策略选择有多种。在不同参数条件下,该非对称信息动态博弈模型可能存在分离均衡、混同均衡和准分离均衡。     

换手率承载了何种市场信息？——基于有限套利视角的分析

换手率作为股票市场信息传递的重要媒介之一,对股票交易活跃程度的衡量发挥着重要作用。研究表明,换手率可以取得显著的负向溢价。然而,换手率究竟承载了何种市场信息,即换手率负向溢价的本质,现有文献并未达成共识。本文从有限套利的视角出发,构建独特的综合套利限制指数,并采用投资组合分析以及Fama-Macbeth回归等方法,详细对比了当前两大主流假说——“流动性溢价”的风险补偿假说及“投资者异质信念”的错误定价假说对换手率溢价的解释能力。研究发现,换手率的负向溢价在套利限制程度高的股票中表现的更加显著和持久。由此说明,换手率负向溢价作为一种市场无效现象,其本质更倾向于由投资者异质信念所引致的错误定价。最后,本文利用融资融券制度的推出作为一个独特的“外生政策冲击”,采用DID方法增加了上述结论的可信性。     

固定执行价格下回望看涨期权保险精算定价

利用保险精算方法,将期权定价问题转化为纯保费确定问题,根据股票价格过程的实际概率测度推导出了无风险利率为常数时,固定执行价格下回望看涨期权定价公式,验证了当标的资产的期望收益率等于无风险利率时,保险精算定价和风险中性定价的一致性.最后通过实例分析了保险精算价格和风险中性价格的差异,并利用Matlab编程得到了保险精算价格与标的资产期望收益率之间的关系.     

广义Black-Scholes模型期权定价新方法--保险精算方法

利用公平保费原则和价格过程的实际概率测度推广了Mogens Bladt和Tina Hviid Rydberg的结果．在无中间红利和有中间红利两种情况下，把Black-Scholes模型推广到无风险资产(债券或银行存款)具有时间相依的利率和风险资产(股票)也具有时间相依的连续复利预期收益率和波动率的情况，在此情况下获得了欧式期权的精确定价公式以及买权与卖权之间的平价关系．给出了风险资产(股票)具有随机连续复利预期收益率和随机波动率的广义Black-Scholes模型的期权定价的一般方法．利用保险精算方法给出了股票价格遵循广义Ornstein-Uhlenback过程模型的欧式期权的精确定价公式和买权和卖权之间的平价关系．     

依赖时间参数的几种有固定执行价格的亚式期权定价

本文在假定标的资产模型依赖时间参数（即无风险利率,标的资产的期望收益率,波动率及红利率）,利用已建立的亚式期权定价模型,讨论了上限型期权、抵付型期权、双向型期权等,得到相应的期权定价解析公式．     

基于投资者情绪的市场均衡分析

在行为金融研究框架下,通过分析情绪投资者与理性投资者的市场均衡条件,构建基于投资者情绪的资产定价模型,并对模型进行了数值模拟。结果表明,投资者情绪是影响资产价格的重要因素:被情绪投资者高估的资产,其回报将下降;被情绪投资者低估的资产,其回报将增加;资产回报的变化程度与情绪投资者卖出低估资产的份额正相关,与资产预期回报金额的相关系数负相关;并且,乐观情绪与悲观情绪对资产价格的作用是非对称的。     

A jump model for fads in asset prices under asymmetric information

This paper addresses how asymmetric information, fads and Lévy jumps in the price of an asset affect the optimal portfolio strategies and maximum expected utilities of two distinct classes of rational investors in a financial market. We obtain the investors’ optimal portfolios and maximum expected logarithmic utilities and show that the optimal portfolio of each investor is more or less than its Merton optimal. Our approximation results suggest that jumps reduce the excess asymptotic utility of the informed investor relative to that of uninformed investor, and hence jump risk could be helpful for market efficiency as an indirect reducer of information asymmetry. Our study also suggests that investors should pay more attention to the overall variance of the asset pricing process when jumps exist in fads models. Moreover, if there are very little or too much fads, then the informed investor has no utility advantage in the long run.     

Mean-variance Hedging for Pricing European-type Contingent Claims with Transaction Costs

In this paper,a European-type contingent claim pricing problem with transaction costs is considered by a mean-variance hedging argument.The investor has to pay transaction costs which areproportional to the amount of stock transacted.The writer‘‘s hedging object is to minimize the hedgingrisk,defined as the variance of hedging error at expiration,with a proper expected excess return level.At first, we consider the mean-variance hedging problem:for initial hedging wealth f,maximizing the excess expected return under the minimum hedging risk level V0.On the other hand,we consider a mean-variance portfolio problem,which is to maximize the expected return with initial wealth 0 under the same risk level V0.The minimum initial hedging wealth f,which can offset the difference of the maximum expected return of these two problems,is the writer‘s price.     

Impact of risk aversion and belief heterogeneity on trading of defaultable claims

This paper studies the problem of pricing and trading of defaultable claims among investors with heterogeneous risk preferences and market views. Based on the utility-indifference pricing methodology, we construct the bid-ask spreads for risk-averse buyers and sellers, and show that the spreads widen as risk aversion or trading volume increases. Moreover, we analyze the buyer’s optimal static trading position under various market settings, including (i) when the market pricing rule is linear, and (ii) when the counterparty—single or multiple sellers—may have different nonlinear pricing rules generated by risk aversion and belief heterogeneity. For defaultable bonds and credit default swaps, we provide explicit formulas for the optimal trading positions, and examine the combined effect of risk aversions and beliefs. In particular, we find that belief heterogeneity, rather than the difference in risk aversion, is crucial to trigger a trade.     

Multiple Priors and Asset Pricing

The asset pricing implications of a statistical model consistent with multiple priors, or beliefs about return distributions, are developed. It is shown that quite generally equilibrium differences in mean returns across priors are to be explained in terms of perceived risk differences between these priors. Advances in filtering theory are employed on time series data to filter all the multiple state conditional components of risks and rewards. It is then observed that excess return differentials across priors are broadly consistent with required risk compensations under these priors, though the sharp hypothesis of zero intercept and unit slope is rejected. The filtered results also deliver numerous other interesting statistics. Here we focus on the construction of long horizon return distributions from data on daily returns using a Markov chain approach to incorporate stochasticity in elementary risk characterizations like volatility, skewness and kurtosis.      

基于动态调整的Copula-非线性分位数回归资产组合优化

为优化资产组合方案,考虑单资产分布的非对称性、异方差性、尖峰厚尾性等特征,资产之间的时变非线性相关性,建立了Copula-非线性分位数回归模型。本文的创新与特色,一是通过构建期望超额收益率与考虑动态损失厌恶效应的VaR比率函数,确定了目标函数的表达式,改变了使用超额收益率标准差度量风险,而实证研究中更关注资产的损失风险而非全部风险,未考虑投资者对于收益与损失非对称偏好的不足;二是通过建立基于支持向量机的非线性分位数回归模型,确定了边缘分布函数表达式,解决了普通模型无法处理非对称、非线性,依赖于分布假设的不足;三是通过构建混合Copula函数,确保能够有效捕捉金融市场中的尾部相关、非对称性,完善了刻画资产之间相关关系的模式;四是通过建立风险非线性叠加的资产总风险评价模型,确定了资产组合总风险的表达式,弥补了现有风险评价模型未考虑资产间的相关性的不足。实证结果表明,本文建立的模型预测性能高于其它模型,该模型有更高的VaR比率值,在单位风险下能够获得更高的资产组合效果。     

Valuation of variable annuities with Guaranteed Minimum Withdrawal Benefit under stochastic interest rate

This paper develops an efficient direct integration method for pricing of the variable annuity (VA) with guarantees in the case of stochastic interest rate. In particular, we focus on pricing VA with Guaranteed Minimum Withdrawal Benefit (GMWB) that promises to return the entire initial investment through withdrawals and the remaining account balance at maturity. Under the optimal (dynamic) withdrawal strategy of a policyholder, GMWB pricing becomes an optimal stochastic control problem that can be solved using backward recursion Bellman equation. Optimal decision becomes a function of not only the underlying asset but also interest rate. Presently our method is applied to the Vasicek interest rate model, but it is applicable to any model when transition density of the underlying asset and interest rate is known in closed-form or can be evaluated efficiently. Using bond price as a numéraire the required expectations in the backward recursion are reduced to two-dimensional integrals calculated through a high order Gauss–Hermite quadrature applied on a two-dimensional cubic spline interpolation. The quadrature is applied after a rotational transformation to the variables corresponding to the principal axes of the bivariate transition density, which empirically was observed to be more accurate than the use of Cholesky transformation. Numerical comparison demonstrates that the new algorithm is significantly faster than the partial differential equation or Monte Carlo methods. For pricing of GMWB with dynamic withdrawal strategy, we found that for positive correlation between the underlying asset and interest rate, the GMWB price under the stochastic interest rate is significantly higher compared to the case of deterministic interest rate, while for negative correlation the difference is less but still significant. In the case of GMWB with predefined (static) withdrawal strategy, for negative correlation, the difference in prices between stochastic and deterministic interest rate cases is not material while for positive correlation the difference is still significant. The algorithm can be easily adapted to solve similar stochastic control problems with two stochastic variables possibly affected by control. Application to numerical pricing of Asian, barrier and other financial derivatives with a single risky asset under stochastic interest rate is also straightforward.