跳扩散模型下基于CRRA效用最大化的资产负债管理

考虑不完备情况下资产和负债对投资者的影响,构建风险资产的价格和投资者的外生负债均服从跳扩散随机过程,利用动态规划和终端时刻资产负债比率的期望效用最大化的方法,得到相应的HJB方程和验证性定理,进而获得最优投资策略和最优值函数的解析表达式。研究发现:(1)当前资产负债比率不影响最优投资策略,但影响最优值函数。(2)最优投资策略与风险资产的预期收益率正相关,与风险资产波动率负相关。跳扩散情形下,风险偏好对最优投资策略没有影响,而无跳扩散情形下,最优投资策略随着风险偏好的增加而增大。(3)值函数随着外生负债波动率σL的增大而增大。不论何种情形最优值函数均随外生负债预期增长率的增大而减小。     

周期风险模型下的保险基金最优投资研究

考虑周期风险模型下保险人的最优投资问题.假设保险人可投资于多种风险资产,投资目标是最大化风险过程的调节系数.当风险资产的价格过程服从几何布朗运动时,采用鞅方法给出保险人破产概率的指数型上界,得到了最优投资策略的解析解.最后根据国内股票市场的实际数据进行了实证分析.     

下边风险测度下养老基金的最优资产配置

以半方差作为下边风险测度,考虑了缴费确定型养老基金的投资策略问题.利用鞅方法求得了最优资产配置的解析解.结果表明最优的资产配置策略分为三部分:债券保值策略,投机策略及一揽子债券的卖空策略,且风险资产的最优投资比例与利率水平及缴费率负相关,与设定的目标值正相关.结论证实了"生活方式"投资的合理性.     

S型效用下比例再保险的最优投资策略

本文引入了行为金融学中的损失厌恶概念,研究考虑损失厌恶时保险公司的最优投资再保险问题.在损失厌恶下,保险公司面对盈利时是风险厌恶者,而遭受损失时转为风险追求者,因此本文采用S型效用函数,并以终端财富的效用最大化为目标求解保险公司的最优策略.假定保险公司的盈余过程服从经典的Cramer-Lundberg模型,可将资产投资于一种无风险资产和一种服从几何布朗运动的风险资产,且可以通过向再保险公司购买比例再保险来分散风险、稳定经营.通过构造鞅过程,运用鞅方法和拉格朗日对偶法求解出最优策略与最优财富.最后进行数值分析,更加直观地解释了各经济参数对财富值和投资策略的影响.     

考虑基准资产的多阶段时间一致投资-再保险策略优化

区别于其它机构投资者,保险公司将面临由保险索赔和证券投资所带来的双重风险。因此,在实际投资过程中,保险公司往往会将某种具有相对稳定收益的资产或组合作为基准,以期为其带来更加持续稳定的收益。然而,已有相关研究多数在连续框架下讨论保险公司的最优投资-再保险的策略优化问题,且没有考虑基准资产对投资-再保险策略的影响。本文首次在多阶段均值-方差框架下,将基准资产考虑到保险公司的投资-再保险策略优化当中。运用倒向递推法分别求出保险公司的时间一致投资-再保险策略和相应值函数的解析表达式。数值分析表明:(1)在给定风险厌恶系数下,相比于不考虑基准资产的投资-再保险策略,基准资产的考虑会促使决策者愿意在投资过程中承担更大的风险;(2)考虑基准的投资-再保险策略能够有效地跟踪基准的收益过程。此外,样本外评价结果进一步验证了考虑基准资产的时间一致投资策略的确可以为投资者带来更多的投资回报。     

动态投资组合保险模型优化研究

基于Merton(1971)的最优消费和投资组合策略模型,利用无风险资产、风险资产复制卖权的方法,建立连续时间条件下的动态投资组合保险模型.在连续时间条件下,把投资者的个人跨期动态投资组合保险决策问题转换为一个静态的效用最大化问题,解出组合保险者最优财富水平对应的最优策略,比较其与Merton的最优投资消费模型投资策略的异同,结果显示参与保险的投资者最优策略与其所拥有的财富无关,与市场风险相关,即市场风险越高,对投资组合保险的需求越大.     

通胀下带激励的对冲基金最优投资

本文在展望理论的框架下,研究了通胀等因素对于带有激励费的对冲基金管理者最优投资策略的影响.对冲基金管理者在风险资产和无风险资产中进行投资,首先利用伊藤公式推导了通胀折现的风险资产价格动力学方程.然后基于考虑通胀折现因素后的终端财富预期效用最大化标准,利用鞅方法推导了最优投资策略的显式解.最后对理论结果进行数值模拟,定量分析了通胀因素,激励费和对冲基金管理者在基金中持有的股本对最优投资策略的影响.     

基于收益序列相关的动态投资组合选择——动态均值-方差模型

以动态均值-方差模型研究基于收益序列相关的投资组合选择.利用嵌入法将动态均值-方差模型嵌入到二次效用模型当中,通过动态规划方法求得最优投资策略和有效边界的解析形式.还得到一个反映风险资产动态投资价值的指标,它能包涵序列相关性的影响,在静态情形下,该指标是夏普指数绝对值的单调递增光滑变换.风险资产投资价值影响最优投资,并决定有效边界斜率.最优投资策略使期望终期财富向目标值趋近,该目标值随风险资产投资价值递增.最后以收益服从AR(1)过程为例对最优投资策略进行数值计算,发现序列相关可以对最优策略造成显著影响.     

带有随机收入与时变风险厌恶系数的最优投资-消费问题

本文考虑具有随机收入与时变相对风险厌恶系数的消费者的最优投资-消费问题.假定消费者参与工作获得工资,进行消费并将财富投资到一个风险资产和一个无风险资产,目标是最大化工作期消费和退休时刻财富的期望效用.其中,工资过程是随机的并服从一个几何布朗运动,在不同时刻,消费者对消费的偏好由一个时变的风险厌恶系数刻画.本文假定金融市场是完备的,采用鞅方法求解,得到最优消费与投资的解析表达式,并对最优消费和投资策略进行敏感性分析.结果表明,当消费者拥有时变风险厌恶系数时,初始财富的大小对其最优期望消费路径影响很大.当消费者面临工资风险时,投资策略中出现了新的对冲项.当消费者流动性财富增大时,消费者消费-收入比增大,但绝对消费水平的变化不确定.     

基于滚动经济回撤约束和下半方差的最优投资组合策略

最大回撤和下半方差均是投资者在实际投资过程中非常关注的风险指标.本文创造性地将这两个风险指标纳入投资组合分析框架,提出了基于风险资产滚动经济回撤约束和下半方差的最优投资组合策略(REDP-LSV策略).该策略以风险资产滚动经济最大回撤为约束条件,以风险资产的下半方差代替方差,研究了投资组合中风险资产的动态配置过程,并给出了解析解.分别采用模拟的实验数据以及中国市场实际风险资产数据,研究了投资组合中包含一种风险资产和两种风险资产的情况,结果均显示REDP-LSV策略能很好地控制最大回撤,且更能提高投资绩效.     

Optimal investment with multiple risky assets under short-selling prohibition in a periodic environment

In this paper,the surplus process is assumed to be a periodic risk model and the insurer is allowed to invest in multiple risky assets described by the Black-Scholes market model.Under short-selling prohibition,the authors consider the optimal investment from an insurer’s point of view by maximizing the adjustment coefficient and the expected exponential utility of wealth at one period, respectively.It is shown that the optimal strategies of both of optimization problems are to invest a fixed amount of money in each risky asset.     

Heston模型下考虑工资风险和保费退还条款的DC型养老金时间一致性投资策略

DC型养老金投资者通常可以将保费投资于金融市场中无风险资产、风险资产以及通胀指数化债券3种资产。在均值-方差准则下，为了充分考虑市场风险因素和保障参保人利益，将通胀风险、波动风险、工资风险以及保费退还条款引进投资模型中。利用博弈论思想和随机最优控制技术，通过求解一个扩展HJB方程组，得到了最优时间一致性投资策略和有效前沿的解析表达。最后，通过数值分析比较了有、无保费退还条款两种情形下的最优投资策略。此外，还分析了一些主要参数对最优投资策略和有效前沿的影响，并给出了经济意义上的解释。     

Optimal investment problem for an insurer and a reinsurer

This paper studies the optimal investment problem for an insurer and a reinsurer. The basic claim process is assumed to follow a Brownian motion with drift and the insurer can purchase proportional reinsurance from the reinsurer. The insurer and the reinsurer are allowed to invest in a risk-free asset and a risky asset. Moreover, the authors consider the correlation between the claim process and the price process of the risky asset. The authors ?rst study the optimization problem of maximizing the expected exponential utility of terminal wealth for the insurer. Then with the optimal reinsurance strategy chosen by the insurer, the authors consider two optimization problems for the reinsurer: The problem of maximizing the expected exponential utility of terminal wealth and the problem of minimizing the ruin probability. By solving the corresponding Hamilton-Jacobi-Bellman equations, the authors derive the optimal reinsurance and investment strategies, explicitly. Finally, the authors illustrate the equality of the reinsurer's optimal investment strategies under the two cases.     

Worst-Case Investment Strategy with Delay

This paper considers a worst-case investment optimization problem with delay for a fund manager who is in a crash-threatened financial market. Driven by existing of capital inflow/outflow related to history performance, we investigate the optimal investment strategies under the worst-case scenario and the stochastic control framework with delay. The financial market is assumed to be either in a normal state(crash-free) or in a crash state. In the normal state the prices of risky assets behave as geometric Brownian motion, and in the crash state the prices of risky assets suddenly drop by a certain relative amount, which induces to a dropping of the total wealth relative to that of crash-free state. We obtain the ordinary differential equations satisfied by the optimal investment strategies and the optimal value functions under the power and exponential utilities, respectively. Finally, a numerical simulation is provided to illustrate the sensitivity of the optimal strategies with respective to the model parameters.     

Optimal multi-asset investment with no-shorting constraint under mean-variance criterion for an insurer

This paper considers the optimal investment strategy for an insurer under the criterion of mean-variance. The risk process is a compound Poisson process and the insurer can invest in a risk-free asset and multiple risky assets. This paper obtains the optimal investment policy using the stochastic linear quadratic (LQ) control theory with no-shorting constraint. Then the efficient strategy (optimal investment strategy) and efficient frontier are derived explicitly by a verification theorem with the viscosity solution of Hamilton-Jacobi-Bellman (HJB) equation.     

Optimal reinsurance and investment strategies for insurers with regime-switching and state-dependent utility function

This paper considers a proportional reinsurance-investment problem and an excess-of-loss reinsurance-investment problem for an insurer, where price processes of the risky assets and wealth process of the insurer are both described by Markovian regime switching. The target of the insurer is assumed to maximize the expected exponential utility from her terminal wealth with a state-dependent utility function. By employing the dynamic programming approach, the optimal value functions and the optimal reinsurance-investment strategies are derived. In addition, the impact of some parameters on the optimal strategies and the optimal value functions is analyzed, and lots of interesting results are discovered, such as the conclusion that excess-of-loss reinsurance is better than proportional reinsurance is not held in the regime-switching jump-diffusion model.     

财富约束条件下损失厌恶投资者的动态投资组合选择

在完全市场框架下, 假定投资者是损失厌恶的, 研究了财富非负和带有基准下限约束条件下一般情形的动态投资组合选择模型. 利用鞅方法,分别获得了投资者的最优期末财富水平, 证明了相应的拉格朗日乘子的存在唯一性. 分析了这些解的性质, 并且和传统风险厌恶投资者的最优解进行了比较. 最后讨论了一个具体例子, 给出了最优财富过程和最优投资策略的解析表达式. 通过理论的结果和图形的显示, 可以发现损失厌恶投资者的最优财富随着市场状态的变化会出现突变, 如果考虑基准下限约束, 则其投资策略相对保守, 可以避免由于突变所造成的大的损失.     

Optimal Investment with Multiple Risky Assets for an Insurer with Modified Periodic Risk Process

This paper considers the optimal investment problem for an insurer in the sense of maximizing the adjustment coefficient of the risk process.The authors propose a modified periodic risk model in which the periodic risk process is perturbed by a standard Brownian motion.The insurer can invest in multiple risky assets and one risk-free asset and the correlations between the risky assets and the risk process are considered.Optimal strategy is obtained explicitly,which is a function of time and related to the risk process.The effects of market parameters on the optimal strategy are discussed and a numerical example is also given.