跳扩散最优控制的随机最大值原理及在金融中的应用

讨论了由金融市场中投资组合和消费选择问题引出的一类最优控制问题,投资者的期望效用是常数相对风险厌恶(CRRA)情形.在跳扩散框架下,利用古典变分法得到了一个局部随机最大值原理.结果应用到最优投资组合和消费选择策略问题,得到了状态反馈形式的显式最优解.     

完备市场下的均衡和财富优化

针对跳扩散模型中的优化与均衡问题,利用鞅方法和随机点过程理论,建立了跳扩散模型下的均衡市场,分析了市场中的财富优化问题,给出了均衡大宗商品现货价格、最优财富过程、最优投资组合及最优消费过程.     

部分信息情形下利率非零时的最优消费投资模型研究

考虑了部分信息情形下市场利率非零时的最优消费投资模型,讨论了相应的最优消费投资策略.最后探讨了当扩散系数可逆且漂移系数服从已知分布时的贝叶斯特例,给出了最优交易策略的明确表达式.     

跳—扩散过程下带实业项目的保险最优决策

为了考虑一类带有实业项目投资的保险最优投资策略问题,假定保险公司盈余服从跳-扩散过程,在最小化保险公司破产概率准则下,使用动态规划原理建立了线性消费率下保险资金最优投资选择模型,通过求解HJB方程得到了最优投资决策和最小破产概率的解析式解,最后分析了线性消费、索赔强度、索赔额以及实业项目投资额对最小化破产概率和最优投资策略的影响.     

跳-扩散模型下相对收益过程带停时的均值-方差随机控制

针对跳扩散模型下鞅测度不唯一的问题,利用识别定理和Riccati方程研究了跳扩散模型下带停时的均值-方差随机控制问题,得到了相对收益过程最优投资策略的显式解及相应的最优停时,并且给出了在最优停止时间的均值方差有效边界.     

最优消费投资的动态经济模型研究（I）

本文研究了金融市场上投资者消费效用优化的随机控制问题。设金融市场上有一个局部无风险的资产和ｄ个风险资产,其价格服从连续的Ｉｔｏ模型。在效用折扣过程为有限分段函数情形下,得出了关于目前财富反馈形式的最优消费投资公式。     

考虑红利支付与提前退休的最优投资组合

研究了在经济代理人通过不可逆退休时间选择来调整劳动时间框架下的最优消费和投资问题,主要考虑风险资产派发红利的情形.运用随机控制方法,求解使得消费-闲暇预期效用最大化的最优策略.最优投资组合及最优退休时刻表明,代理人在为提前退休积累财富的同时,也能最佳享受消费和闲暇所带来的快乐.     

部分信息下的最优投资消费策略显示解

本文讨论投资者极大化生命期期望消费效用的最优化问题,在较一般情形下,给出了由证券交易价格（部分信息）决定的最优投资消费策略显示解。     

含有信用风险的跳扩散市场的最优组合选择

假定投资者将其财富分配在这样两种风险资产中,一种是股票,价格服从跳跃扩散过程;一种是有信用风险的债券,其价格服从复合泊松过程.在均值-方差准则下通过最优控制原理来研究投资者的最优投资策略选择问题,得到了最优投资策略及有效边界,最后通过数值例子分析了违约强度、债券预期收益率以及目标财富对最优投资策略的影响.     

带有交易成本和红利的最优消费投资策略研究

本文利用HJB方程粘性解理论,考虑带有红利收益和交易成本后,对现有最优消费投资模型作了推广,研究了投资者在带有红利和交易成本情形下的最优消费投资策略。     

Strong approximations and sequential change-point analysis for diffusion processes

In this paper ergodic diffusion processes depending on a parameter in the drift are considered under the assumption that the processes can be observed continuously. Strong approximations by Wiener processes for a stochastic integral and for the estimator process constructed by the one-step procedure of Le Cam are obtained. Applying these approximations, a CUSUM-type procedure is developed for the sequential testing of changes in the parameter.     

基于跳跃波动率的未定权益定价模型

讨论了具有随机波动率的未定权益定价问题,建立了两状态波动率的股票价格行为模型,在股票价格过程是连续过程、跳风险不可定价的假设下,推导出未定权益的定价公式.     

Moment equations and Hermite expansion for nonlinear stochastic differential equations with application to stock price models

Exact moment equations for nonlinear Itô processes are derived. Taylor expansion of the drift and diffusion coefficients around the first conditional moment gives a hierarchy of coupled moment equations which can be closed by truncation or a Gaussian assumption. The state transition density is expanded into a Hermite orthogonal series with leading Gaussian term and the Fourier coefficients are expressed in terms of the moments. The resulting approximate likelihood is maximized by using a quasi Newton algorithm with BFGS secant updates. A simulation study for the CEV stock price model compares the several approximate likelihood estimators with the Euler approximation and the exact ML estimator (Feller, in Ann Math 54: 173–182, 1951).     

Divergence theorems in path space III: Hypoelliptic diffusions and beyond

Let x denote a diffusion process defined on a closed compact manifold. In an earlier article, the author introduced a new approach to constructing admissible vector fields on the associated space of paths, under the assumption of ellipticity of x. In this article, this method is extended to yield similar results for degenerate diffusion processes. In particular, these results apply to non-elliptic diffusions satisfying Hörmander's condition.     

股价遵循分数跳扩散的混合型双标的两值期权定价

应用风险中性定价原理,研究标的股价服从分数跳扩散过程的混合型双标的两值期权的定价问题,并得出定价公式,并与股价服从标准布朗运动的定价公式做出比较分析.     

随机波动率下股价服从O-U过程的期权定价

假设股票价格遵循指数O-U过程,利用随机分析中的鞅方法,得到了具有随机波动率的欧式期权的定价公式,推广了B-S模型.     

Optimal investment and consumption models with non-linear stock dynamics

We study a generalization of the Merton's original problem of optimal consumption and portfolio choice for a single investor in an intertemporal economy. The agent trades between a bond and a stock account and he may consume out of his bond holdings. The price of the bond is deterministic as opposed to the stock price which is modelled as a diffusion process. The main assumption is that the coefficients of the stock price diffusion are arbitrary nonlinear functions of the underlying process. The investor's goal is to maximize his expected utility from terminal wealth and/or his expected utility of intermediate consumption. The individual preferences are of Constant Relative Risk Aversion (CRRA) type for both the consumption stream and the terminal wealth. Employing a novel transformation, we are able to produce closed form solutions for the value function and the optimal policies. In the absence of intermediate consumption, the value function can be expressed in terms of a power of the solution of a homogeneous linear parabolic equation. When intermediate consumption is allowed, the value function is expressed via the solution of a non-homogeneous linear parabolic equation.     

Microfoundations for diffusion price processes

We study microeconomic foundations of diffusion processes as models of stock price dynamics. To this end, we develop a microscopic model of a stock market with finitely many heterogeneous economic agents, who trade in continuous time, giving rise to an endogeneous pure-jump process describing the evolution of stock prices over time. When the number of agents in the market is large, we show that the price process can be approximated by a diffusion, with price-dependent drift and volatility coefficients that are determined by small excess demands and trading volume in the microscopic model. We extend the microscopic model further by allowing for non-market interactions between agents, to model herd behavior in the market. In this case, price dynamics can be approximated by a process with stochastic volatility. Finally, we demonstrate how heavy-tailed stock returns emerge when agents have a strong tendency towards herd behavior.     

膨胀的Poisson过程及其在金融中的应用

本文定义了一种增量不独立的纯跳过程,称为膨胀的Poisson过程.采用了一个n跳过程来描述股票市场价格运动的规律,并构造了一个货币市场投资组合使得它的市场价值在指定时刻与股票价格相等,且该投资组合的收益被分解成为一个确定性的项和一个膨胀的Poisson项之和.证明了投资投票市场风险大于投资货币市场风险.     

基于跳扩散过程的数据选择权定价

本文在风险中性原理下研究基于跳扩散过程的数据选择权定价问题,推导了标的资产价格服从跳扩散过程的数据选择权的定价公式。