证券组合投资模型优化

以Markowitz证券组合投资理论为基础,对于几种不同证券组合投资模型分别考虑了证券组合的收益,风险,交易费等因素条件下对模型进行了优化,并对文中模型做了进一步的扩展。为投资者正确选择证券组合投资的最优策略及应用方面提供参考。     

浅析现代投资组合理论

投资组合理论是资本市场理论的重要组成部分,现代投资组合理论是马科维茨在传统的投资理论的基础上,应用概率论和线性代数的方法以及偏好和效用分析理论建立的一套系统的理论模型.投资组合理论主要是研究人们在预期收入受到多种不确定因素影响的情况下,如何进行分散化投资来规避投资中的非系统风险,实现投资收益的最大化.本文重点介绍由两种证券的风险和收益确定该组合的风险、收益,可行集及多种证券组合中最佳组合的选择.     

基于确定性偏好的投资组合选择

文章在对马科维茨证券投资组合模型简要评述的基础上，针对投资者可选标的证券信息集非对称的现实，依据确定性偏好原理，将投资者对可选标的证券信息的确定性程度转换成偏好次序关系，同时结合行为金融学中的前景理论，依确定性偏好次序规则来确定权重函数，并在价值函数-风险的框架下探讨了证券投资组合模型的构建及其最优解，从而在行为金融理论下扩展了马氏证券投资组合模型。实证分析表明，我国证券市场投资者基本是采用线性赋权方式来处理非对称信息集下的投资组合选择的。     

行为金融学：公司股利政策研究的新视角

行为金融学是在对现代金融理论的挑战和质疑的背景下形成的。现代金融理论是以理性人假设和EMH为基础发展起来的关于投资者在最优投资组合决策和酱市场均衡状态下如何决定各种证券价格的理论体系。     

不确定收益的最优投资组合模型

投资组合理论是金融学乃至整个经济学领域一个非常激动人心的部分,涌现出了大量的投资模型和理论,这些模型大多采用概率论或者模糊理论方法处理投资中的不确定性,对于缺乏样本数据这种情形(如购买的是新出现的证券)建立的模型甚少。针对这种投资情况,利用不确定理论考虑了马科维茨的均值——方差投资组合模型的变形形式,建立了不确定收益的最优投资组合选择模型,进一步丰富了证券投资理论。     

投资组合理论在实体项目投资中的应用

现代投资组合理论在西方发展了近半个世纪,在理论上日趋成熟,同时在经济实践中日益受到广泛重视和利用。然而,投资组合理论更多的是被应用于证券的投资,而在实体项目投资中却很少应用,但该理论作为最优投资组合的决策工具,在实体项目投资选择上同样具有相当的指导作用。     

对当代证券投资组合全球化发展态势的研究

面对当今新的世界经济形势,金融行业的各个方面都迎来了新的发展机遇和挑战.同样证券投资也不例外.本文主要是对当代证券投资组合理论的基本思想进行相关的阐述,同时指出了当代证券投资组合发展的三个方向,并对当代证券投资组合全球化发展态势进行研究,继而提出了当代证券投资组合全球化发展态势的思路.     

分形理论与证券投资组合的风险分散

比较传统理论下的证券投资组合与分形理论下的证券投资组合的证券投资分散化对风险降低的程度,通过分析得出:实际中分散化投资策略并未达到正态分布假设下投资组合理论所认为的风险降低程度。     

波士顿矩阵在高新技术企业融资策略上的应用研究

一、波士顿矩阵基本原理波士顿矩阵是由波士顿集团在上世纪70年代初开发的。波士顿矩阵的精髓在于把战略规划和资本预算紧密结合起来,把一个复杂的企业行为用两个重要的衡量指标划分为四种不同的类型,用四个相对简单的分析来应对复杂的战略问题。该矩阵帮助公司确定哪些业务应该重点投资,哪些业务应该从投资组合中剔除,从而使投资组合达到最佳状态。     

含交易费用的证券投资模型

以Markowitz证券组合投资理论为基础,本文对证券投资中存在交易费用问题进行研究。并分别对包含无风险证券投资和有追加投资额两种情况下,给出了含有买进和卖出交易费用的投资决策模型。     

A NOTE ON THE QUANTILE FORMULATION

Many investment models in discrete or continuous‐time settings boil down to maximizing an objective of the quantile function of the decision variable. This quantile optimization problem is known as the quantile formulation of the original investment problem. Under certain monotonicity assumptions, several schemes to solve such quantile optimization problems have been proposed in the literature. In this paper, we propose a change‐of‐variable and relaxation method to solve the quantile optimization problems without using the calculus of variations or making any monotonicity assumptions. The method is demonstrated through a portfolio choice problem under rank‐dependent utility theory (RDUT). We show that this problem is equivalent to a classical Merton's portfolio choice problem under expected utility theory with the same utility function but a different pricing kernel explicitly determined by the given pricing kernel and probability weighting function. With this result, the feasibility, well‐posedness, attainability, and uniqueness issues for the portfolio choice problem under RDUT are solved. It is also shown that solving functional optimization problems may reduce to solving probabilistic optimization problems. The method is applicable to general models with law‐invariant preference measures including portfolio choice models under cumulative prospect theory (CPT) or RDUT, Yaari's dual model, Lopes' SP/A model, and optimal stopping models under CPT or RDUT.     

Optimal Sure Portfolio Plans

This paper is a sequel to the author's "Certainty Equivalence in the Continuous-Time Portfolio-cum-Saving Model" in Applied Stochastic Analysis (eds. M. H. A. Davis and R. J. Elliot), where a model of optimal accumulation of capital and portfolio choice over an infinite horizon in continuous time was considered in which the vector process representing returns to investment is a general semimartingale with independent increments and the welfare functional has the discounted constant relative risk aversion (CRRA) form. A problem of optimal choice of a sure (i.e., nonrandom portfolio plan can be defined in such a way that solutions of this problem correspond to solutions of optimal choice of a portfolio-cum-saving plan, provided that the distant future is sufficiently discounted. This has been proved in the earlier paper, and is in part proved again here by different methods. Using the canonical representation of a PII-semimartingale, a formula of Lévy-Khinchin type is derived for the bilateral Laplace transform of the compound interest process generated by a sure portfolio plan. With its aid. the existence of an optimal sure portfolio plan is proved under suitable conditions, and various causes of nonexistence are identified. Programming conditions characterizing an optimal sure portfolio plan are also obtained.     

MEAN–VARIANCE PORTFOLIO CHOICE: QUADRATIC PARTIAL HEDGING

In this paper we investigate the problem of mean–variance portfolio choice with bankruptcy prohibition. For incomplete markets with continuous assets' price processes and for complete markets, it is shown that the mean–variance efficient portfolios can be expressed as the optimal strategies of partial hedging for quadratic loss function. Thus, mean–variance portfolio choice, in these cases, can be viewed as expected utility maximization with non-negative marginal utility.     

OPTIMAL PORTFOLIO, CONSUMPTION-LEISURE AND RETIREMENT CHOICE PROBLEM WITH CES UTILITY

We study optimal portfolio, consumption-leisure and retirement choice of an infinitely lived economic agent whose instantaneous preference is characterized by a constant elasticity of substitution (CES) function of consumption and leisure. We integrate in one model the optimal consumption-leisure-work choice, the optimal portfolio selection, and the optimal stopping problem in which the agent chooses her retirement time. The economic agent derives utility from both consumption and leisure, and is able to adjust her supply of labor flexibly above a certain minimum work-hour, and also has a retirement option. We solve the problem analytically by considering a variational inequality arising from the dual functions of the optimal stopping problem. The optimal retirement time is characterized as the first time when her wealth exceeds a certain critical level. We provide the critical wealth level for retirement and characterize the optimal consumption-leisure and portfolio policies before and after retirement in closed forms. We also derive properties of the optimal policies. In particular, we show that consumption in general jumps around retirement.     

Book Reviews

In a world of limited resources, marketing managers tasked to deliver shareholder value face decisions about how to maximise the returns on their marketing portfolio. Risk is less often considered. In finance the picture is very different; financial portfolio management is concerned with both risk and returns. The central innovation in this paper is the application of modern portfolio theory (MPT) to the management of marketing portfolios in food retailing and in drinks manufacturing. The authors develop a model that calculates an efficient frontier of marketing portfolios that maximise overall return within certain risk constraints, first for a simple two-segment marketing world and then for a more realistic multi-segment portfolio. However, marketing portfolios differ from financial ones in the sense that the allocation of marketing spend affects the returns from the portfolio. Therefore, a second innovation, an extension of MPT to take account of marketing spend allocation decisions, has been developed. Using this model, marketers can determine the risk and the returns of marketing investments, helping them select an optimal portfolio. This would go some way to ensuring that marketing contributes to shareholder value creation, currently one of its major challenges.     

PORTFOLIO LIQUIDATION IN DARK POOLS IN CONTINUOUS TIME

We consider an illiquid financial market where a risk averse investor has to liquidate a portfolio within a finite time horizon [0, T] and can trade continuously at a traditional exchange (the “primary venue”) and in a dark pool. At the primary venue, trading yields a linear price impact. In the dark pool, no price impact costs arise but order execution is uncertain, modeled by a multidimensional Poisson process. We characterize the costs of trading by a linear‐quadratic functional which incorporates both the price impact costs of trading at the primary exchange and the market risk of the position. The solution of the cost minimization problem is characterized by a matrix differential equation with singular boundary condition; by means of stochastic control theory, we provide a verification argument. If a single‐asset position is to be liquidated, the investor slowly trades out of her position at the primary venue, with the remainder being placed in the dark pool at any point in time. For multi‐asset liquidations this is generally not the case; for example, it can be optimal to oversize orders in the dark pool in order to turn a poorly balanced portfolio into a portfolio bearing less risk.     

Adoption of multiple electronic marketplaces: Antecedents from a grounded theory study

To achieve economies of scope, most motor carriers combine long-term contracts with shippers and brokers with periodic spot assignments found on electronic marketplaces (EMs). While previous research has addressed how carriers adopt an EM, we know little about factors that influence carriers to adopt multiple EMs. Given the rise of the platform economy of the trucking industry, we chose to address this gap and generate mid-range theory on adopting multiple EMs in a logistics context. To do this, we applied grounded theory and conducted 23 interviews with motor carriers and EM experts in North America and Europe until we reached theoretical saturation. Our findings reveal that many motor carriers adopt a portfolio of different EMs, and that their awareness of platforms, expected and realized benefits, attitude, and vigilance determine how they configure their EM portfolios. The implication for existing theory is that, while previous studies depicted EM adoption from a single-system perspective, we found that it is actually a continuous selection process that follows a portfolio perspective. Our paper also has implications for practice in that it illuminates the rationales behind EM portfolio development and identifies actionable factors that can help managers configure stronger portfolios.     

PORTFOLIO OPTIMIZATION WITH JUMPS AND UNOBSERVABLE INTENSITY PROCESS

We consider a financial market with one bond and one stock. The dynamics of the stock price process allow jumps which occur according to a Markov-modulated Poisson process. We assume that there is an investor who is only able to observe the stock price process and not the driving Markov chain. The investor's aim is to maximize the expected utility of terminal wealth. Using a classical result from filter theory it is possible to reduce this problem with partial observation to one with complete observation. With the help of a generalized Hamilton–Jacobi–Bellman equation where we replace the derivative by Clarke's generalized gradient, we identify an optimal portfolio strategy. Finally, we discuss some special cases of this model and prove several properties of the optimal portfolio strategy. In particular, we derive bounds and discuss the influence of uncertainty on the optimal portfolio strategy.     

HEDGING AND PORTFOLIO OPTIMIZATION UNDER TRANSACTION COSTS: A MARTINGALE APPROACH12

We derive a formula for the minimal initial wealth needed to hedge an arbitrary contingent claim in a continuous-time model with proportional transaction costs; the expression obtained can be interpreted as the supremum of expected discounted values of the claim, over all (pairs of) probability measures under which the “wealth process” is a supermartingale. Next, we prove the existence of an optimal solution to the portfolio optimization problem of maximizing utility from terminal wealth in the same model, we also characterize this solution via a transformation to a hedging problem: the optimal portfolio is the one that hedges the inverse of marginal utility evaluated at the shadow state-price density solving the corresponding dual problem, if such exists. We can then use the optimal shadow state-price density for pricing contingent claims in this market. the mathematical tools are those of continuous-time martingales, convex analysis, functional analysis, and duality theory.     

PORTFOLIO MANAGEMENT WITH TRANSACTION COSTS: AN ASYMPTOTIC ANALYSIS OF THE MORTON AND PLISKA MODEL

We examine the Morton and Pliska (1993) model for the optimal management of a portfolio when there are transaction costs proportional to a fixed fraction of the portfolio value. We analyze this model in the realistic case of small transaction costs by conducting a perturbation analysis about the no-transaction-cost solution. Although the full problem is a free-boundary diffusion problem in as many dimensions as there are assets in the portfolio, we find explicit solutions for the optimal trading policy in this limit. This makes the solution for a realistically large number of assets a practical possibility.