跳扩散模型在保险公司投资策略中的应用

利用随机控制理论、HJB方程、最优决策理论等数学工具,研究保险公司保费收入的投资策略问题.假定保险公司盈余过程服从跳扩散过程,保险公司将(1-q)比例的资金投向金融资产,比例q向其它保险公司购买保险(再保险).在目标函数为终止时刻财富期望效用最大的情况下构建一个包含q的HJB方程,基于常利率和随机利率,分别验证了q的存在性,并给出了最优投资策略的显示解和各重要参数对最优投资策略的影响.     

Vasicek利率与Heston模型下的最优投资和再保险

本文主要研究Vasicek随机利率模型下保险公司的最优投资与再保险问题.假设保险公司的盈余过程由带漂移的布朗运动来描述,保险公司通过购买比例再保险来转移索赔风险;同时,将财富投资于由一种无风险资产与一种风险资产组成的金融市场,其中,利率期限结构服从Vasicek利率模型,且风险资产价格过程满足Heston随机波动率模型.利用动态规划原理及变量替换的方法,得到了指数效用下最优投资与再保险策略的显示表达式,并给出数值例子分析了主要模型参数对最优策略的影响.     

基于随机波动的最优广告支出策略

考虑企业在具有随机波动的市场体系中的特殊投资模型一广告支出模型.在典型的动态规划中,投资问题中的值函数一般是用Bellman方程的粘滞解表示的.本文通过指数变换把偏微分(Bellman)方程转变成一个对微分项是半线性的抛物线方程,并证明了其值函数连续解的存在性,在此基础上给出了企业最优广告支出策略.     

基于随机波动的企业的最优组合投资策略

Merton的投资模型拓展到随机波动模型.在典型的动态规划中,投资问题中的值函数一般用Bellman方程的粘滞解表示.本文通过指数变换把偏微分方程转变成一个半线性的抛物线方程,并证明了其值函数连续解的存在性,在此基础上给出了企业的最优组合投资策略及一个投资的例子.     

常利率下Cox风险过程的罚金折现期望函数

本文考虑了常利率环境下Cox风险模型的罚金折现期望值，利用后向差分法，得到了条件期望值与平稳情形时的期望值分别所满足的积分方程．并且，给出了一个强度过程为二状态马尔可夫过程及索赔服从指数分布的例子．     

保险费收取次数为泊松过程下的广义复合泊松风险模型

经典的破产模型是假定保险公司按单位时间常数速率收取保险费，盈余过程{R（t），t≥0中的S（f）=∑i=1^N（t）Y,为一复合泊松过程，本文将保费到达过程推广为一个Poisson过程，同时将S（t）推广为一个广义复合Poisson过程．针对此模型给出了盈余过程的一些性质，得到关于破产概率的一个定理．     

股票收益率的随机波动

设Ｘ_ｎ（ｔ）为第ｎ个投资者在时刻ｔ的投资行为对股票收益率的影响，文［４］证明了｛ｓｕｍ　ｆｒｏｍ　ｎ＝１　ｎ~/Ｘ_ｋ（ｔ）｝弱收敛于一个Ｇａｕｓｓ过程Ｘ_ｔ，本文对Ｘ_ｔ的性质做了进一步的讨论．     

Loeb空间上一类右连续过程最优停止的非标准表示

本文在Loeb空间上得到了右连续左半上连续的随机过程的SRC提升．证明了一个内过程的S-最优停止的存在性,并得到了它的结构性表示．最后证明了一个过程SRC提升的S-最优停止的标准部分即为对应标准过程的最优停止,在Loeb空间上推广了[8]中的结果．     

随机利率下双分红的变保费复合帕斯卡模型

利润最大化风险最小化是保险公司运营所追求的目标,破产概率为公司进行风险决策提供了依据。本文基于随机利率环境下,保费随公司盈余水平调整的双分红复合帕斯卡模型,研究了股份制保险公司的有限时间破产概率。我们证明了公司盈余过程的齐次马氏性,得到了有限时间破产概率的计算方法,最后给出了具体算例。     

关于Q过程跳跃次数的一个注记

本文考虑一类Ｑ过程的跳次数及相应的点过程，证明了与此点过程有关的一个随机积分是平方可积鞅，同时对有关文献中的不足之处作了讨论。     

Ruin problems for a discrete time risk model with random interest rate

In this paper, we study a discrete time risk model with random interest rate. The convergence of the discounted surplus process is proved by using martingale techniques, an expression of ruin probability is obtained, and bounds for ruin probability are included. In the second part of the paper, the distribution of surplus immediately after ruin, the distribution of surplus just before ruin, the joint distribution of the surplus immediately before and after ruin, and the distribution of ruin time are discussed.     

Upper bounds for ruin probabilities under stochastic interest rate and optimal investment strategies

In this paper, we study the upper bounds for ruin probabilities of an insurance company which invests its wealth in a stock and a bond. We assume that the interest rate of the bond is stochastic and it is described by a Cox-Ingersoll-Ross (CIR) model. For the stock price process, we consider both the case of constant volatility (driven by an O-U process) and the case of stochastic volatility (driven by a CIR model). In each case, under certain conditions, we obtain the minimal upper bound for ruin probability as well as the corresponding optimal investment strategy by a pure probabilistic method.     

理赔为一般到达的常利率风险模型

In this paper, we discuss the insurance risk models of general arrrival of claims with con-stant interest force, prove that the surplus process {Xб(Tn), n≥0} at claim occurrence times T. is ahomogeneous Markov skeleton one,and give the distribution of surplus assets prior to and ruin andthe joint distrubutions of the ruin time and them.     

On the time value of absolute ruin with tax

Consider a compound Poisson surplus process of an insurer with debit interest and tax payments. When the portfolio is in a profitable situation, the insurer may pay a certain proportion of the premium income as tax payments. When the portfolio is below zero, the insurer could borrow money at a debit interest rate to continue his/her business. Meanwhile, the insurer will repay the debts from his/her premium income. The negative surplus may return to a positive level except that the surplus is below a certain critical level. In the latter case, we say that absolute ruin occurs. In this paper, we discuss absolute ruin quantities by defining an expected discounted penalty function at absolute ruin. First, a system of integro-differential equations satisfied by the expected discounted penalty function is derived. Second, closed-form expressions for the expected discounted total sum of tax payments until absolute ruin and the Laplace-Stieltjes transform (LST) of the total duration of negative surplus are obtained. Third, for exponential individual claims, closed-form expressions for the absolute ruin probability, the LST of the time to absolute ruin, the distribution function of the deficit at absolute ruin and the expected accumulated discounted tax are given. Fourth, for general individual claim distributions, when the initial surplus goes to infinity, we show that the ratio of the absolute ruin probability with tax to that without tax goes to a positive constant which is greater than one. Finally, we investigate the asymptotic behavior of the absolute ruin probability of a modified risk model where the interest rate on a positive surplus is involved.     

含投资因素的崩溃模型

本文讨论了已推广的保险公司的崩溃模型.本文得到了离散时间的崩溃模型复利情形下的崩溃概率公式,也得出了连续时间的崩溃模型崩溃概率的明确解和Vokterra积分方程.这些结果推广了经典崩溃模型中的相应结果.     

保险公司在固定利率下的离散型破产概率

本提出并讨论了在固有利率下含投资因素、红利分配因素的两种离散型破产模型，分别得出了相应模型下关于保险公司的破产概率、期望寿命的结论，推广散没有考虑利率因素的离散型破产模型的有关结论。     

带息双二项风险模型的破产问题

本文研究了带随机利率的双二项风险模型的破产问题,得到了描述破产严重程度的破产前盈余分布,破产持续时间分布的递推公式,有限时间破产概率的递推公式及终极破产概率满足的积分方程.     

A Markov decision problem in a risk model with interest rate and Markovian environment

We consider the compound binomial model in a Markovian environment presented by Cossette et al.(2004). We modify the model via assuming that the company receives interest on the surplus and a positive real-valued premium per unit time, and introducing a control strategy of periodic dividend payments. A Markov decision problem arises and the control objective is to maximize the cumulative expected discounted dividends paid to the shareholders until ruin minus a discounted penalty for ruin. We show that under the absence of a ceiling of dividend rates the optimal strategy is a conditional band strategy given the current state of the environment process. Under the presence of a ceiling for dividend rates, the character of the optimal control strategy is given. In addition, we offer an algorithm for the optimal strategy and the optimal value function.Numerical results are provided to illustrate the algorithm and the impact of the penalty.     

一类完全离散的经典风险模型的破产概率

本文研究引入利率的完全离散经典风险模型,得到一个有限时间内的破产概率的递推公式,最后给出了一个数值算例.     

On the decomposition of the absolute ruin probability in a perturbed compound Poisson surplus process with debit interest

We consider a compound Poisson surplus process perturbed by diffusion with debit interest. When the surplus is below zero or the company is on deficit, the company is allowed to borrow money at a debit interest rate to continue its business as long as its debt is at a reasonable level. When the surplus of a company is below a certain critical level, the company is no longer profitable, we say that absolute ruin occurs at this situation. In this risk model, absolute ruin may be caused by a claim or by oscillation. Thus, the absolute ruin probability in the model is decomposed as the sum of two absolute ruin probabilities, where one is the probability that absolute ruin is caused by a claim and the other is the probability that absolute ruin is caused by oscillation. In this paper, we first give the integro-differential equations satisfied by the absolute ruin probabilities and then derive the defective renewal equations for the absolute ruin probabilities. Using these defective renewal equations, we derive the asymptotical forms of the absolute ruin probabilities when the distributions of claim sizes are heavy-tailed and light-tailed. Finally, we derive explicit expressions for the absolute ruin probabilities when claim sizes are exponentially distributed.