The consumption–investment decision of a prospect theory household: A two-period model

This study extends the literature on portfolio choice under prospect theory preferences by introducing a two-period life cycle model, where the sufficiently loss averse household decides on optimal consumption and investment in a portfolio with one risk-free and one risky asset. The optimal solution depends primarily on whether the household’s present value of the consumption reference levels is below, equal to, or above the present value of its endowment income. Reference levels below the endowment income are associated with the self-enhancement motive. In this case, the household avoids relative losses in consumption in any present or future state of nature (good or bad). As a result the degree of loss aversion does not directly affect optimal consumption and risk taking activity. Reference levels equal to the endowment income are associated with the belonging motive. An example would be a household comparing to others that belong to the same social class. In this case the household’s optimal consumption is the reference consumption and the household will not invest in the risky asset. Finally, reference levels above the endowment income are associated with the self-improvement motive (or high aspirations). For such high reference levels, households cannot avoid experiencing a relative loss in consumption, either now or in the future. As a result, loss aversion directly affects consumption and risky investment.     

Measuring financial risk and portfolio reversion with time changed tempered stable Lévy processes

Given that underlying assets in financial markets exhibit stylized facts such as leptokurtosis, asymmetry, clustering properties and heteroskedasticity effect, this paper applies the stochastic volatility models driven by tempered stable Lévy processes to construct time changed tempered stable Lévy processes (TSSV) for financial risk measurement and portfolio reversion. The TSSV model framework permits infinite activity jump behaviors of returns dynamics and time varying volatility consistently observed in financial markets by introducing time changing volatility into tempered stable processes which specially refer to normal tempered stable (NTS) distribution as well as classical tempered stable (CTS) distribution, capturing leptokurtosis, fat tailedness and asymmetry features of returns in addition to volatility clustering effect in stochastic volatility. Through employing the analytical characteristic function and fast Fourier transform (FFT) technique, the closed form formulas for probability density function (PDF) of returns, value at risk (VaR) and conditional value at risk (CVaR) can be derived. Finally, in order to forecast extreme events and volatile market, we perform empirical researches on Hangseng index to measure risks and construct portfolio based on risk adjusted reward risk stock selection criteria employing TSSV models, with the stochastic volatility normal tempered stable (NTSSV) model producing superior performances relative to others.     

When do improved covariance matrix estimators enhance portfolio optimization? An empirical comparative study of nine estimators

The use of improved covariance matrix estimators as an alternative to the sample estimator is considered an important approach for enhancing portfolio optimization. Here we empirically compare the performance of nine improved covariance estimation procedures using daily returns of 90 highly capitalized US stocks for the period 1997–2007. We find that the usefulness of covariance matrix estimators strongly depends on the ratio between the estimation period T and the number of stocks N, on the presence or absence of short selling, and on the performance metric considered. When short selling is allowed, several estimation methods achieve a realized risk that is significantly smaller than that obtained with the sample covariance method. This is particularly true when T/N is close to one. Moreover, many estimators reduce the fraction of negative portfolio weights, while little improvement is achieved in the degree of diversification. On the contrary, when short selling is not allowed and T?>?N, the considered methods are unable to outperform the sample covariance in terms of realized risk, but can give much more diversified portfolios than that obtained with the sample covariance. When T?<?N, the use of the sample covariance matrix and of the pseudo-inverse gives portfolios with very poor performance.     

一种改进的不完全指数复制方法

本文在考虑交易成本和投资组合动态调整的基础上,建立混合整数线性规划模型,引入内核搜索分析框架进行近似求解,并利用沪深300进行实证研究。研究发现,一是相比于基本内核搜索法,增强型内核搜索法仅在基准指数成分股数量很大时才会较大幅度提高求解质量;二是考虑投资组合动态调整的模型不仅更稳健,而且跟踪的继承性和保持性更好,尤其适用于单边市场;三是过度刻画现实交易特征一定程度上会降低不完全指数复制模型的复制和预测效果。     

Estimation of the change point of a distribution based on the number of failed test items

This paper discusses the family of life distributions with failure rate functions which decrease initially until a change point and remain constant thereafter. The paper focuses on the estimation for the change point of the failure rate function. While point estimation of the change point of the failure rate function has been discussed by some authors, one can hardly find any existing work on the interval estimation of the change point. In this paper, a method for constructing approximate confidence intervals for the change point is proposed. The proposed approximate confidence intervals are based on the number of failed test items at or before a fixed inspection time. Received: September 1999     

流动性、生命周期与投资组合相异性——中国投资者行为调查实证分析

本文采用Probit和Tobit模型对中国居民的股票市场参与和投资组合的影响因素进行了分析,主要有以下的实证发现:首先,不流动性资产特别是房地产的投资显著影响了投资者的股票市场参与和投资组合,而且影响以“替代”效应或者说“挤出”效应为主。其次,投资者在进行投资组合时极少利用股票市场对其未来现金流所承担的风险进行对冲,也就是说,中国居民投资的“生命周期效应”不明显;第三,中国居民投资的“财富效应”非常显著。财富的增加既增加了居民参与股票市场的概率,也增加了居民参与股票市场的深度。     

Growth Optimal Investment Strategy: The Impact of Reallocation Frequency and Heavy Tails

The strategy to maximize the long‐term growth rate of final wealth (maximum expected log strategy, maximum geometric mean strategy, Kelly criterion) is based on probability theoretic underpinnings and has asymptotic optimality properties. This article reviews the allocation of wealth in a two‐asset economy with one risky asset and a risk‐free asset. It is also shown that the optimal fraction to be invested in the risky asset (i) depends on the length of the basic return period and (ii) is lower for heavy‐tailed log returns than for light‐tailed log returns.     

Portfolio constraints,differences in beliefs and bubbles

I propose an arbitrage-based theory of bubbles in economies with general portfolio constraints and differences in beliefs. I find that, in general, bubbles cannot exist unless the constraints restrict the demand for credit sufficiently to induce low interest rates. Speculation due to heterogeneous beliefs does not cause bubbles. Ruling out bubbles under asymmetric information requires stronger assumptions: the presence of some uninformed agents and mild portfolio restrictions (debt or borrowing constraints), or alternatively, the existence of some impatient and fully informed agents.     

SKU performance and distribution: A large-scale analysis of the role of product characteristics with store scanner data

This study investigates the relationship between distribution and market share across various consumer packaged goods (CPG) categories and specific stock keeping units (SKUs). The study identifies product-related characteristics that result in substantive deviations above or below market shares predicted by the distribution – market share relationship. The association of product price, brand (private label [PL] v. national brand [NB]) and pack size with above (or below) expected market share for a given distribution level is analysed. Results indicate larger pack sizes, PL and medium price levels result in market share above what would be predicted by an SKU’s distribution. This presents a source for competitive advantage in markets driven by push–pull dynamics.     

Is there a diversification “cost” of Shari’ah compliance? Empirical evidence from Malaysian equities

Islamic equity portfolios work with a smaller investment universe given the filtering of non-Shari’ah compliant stocks. It has been theoretically argued that this culminates in suboptimal portfolio diversification, which in turn adversely affects risk-adjusted returns. We offer empirical evidence that such a conceived portfolio diversification “penalty” is far from a foregone conclusion, at least empirically. Our results tend to indicate that Islamic portfolios are not invariably handicapped in terms of portfolio diversification. We also explored dimensions that may account for differences in the relative investment performance between Islamic and conventional portfolios, such as portfolio constraints, short selling and market conditions. We believe this paper is among the first to apply substantial empirical analysis specifically with respect to the portfolio diversification perspective on Islamic equity investments.