Reviewing portfolio strategy

In our work on corporate-level strategy we have often claimed that many, if not most, large corporations are over-diversified. This, we claim, accounts for the popularity of MBOs, LBOs, spinoffs, demergers, unbundling and many other ways of reducing diversification. This article explains, in the form of a letter to a fictitious chief executive, why some forms of diversification lead to value destruction while other forms lead to value creation.     

A commonsense approach to portfolio planning

For the diversified firm, business portfolio planning offers a way of determining its individual businesses' roles and developing a synergistic corporate strategy. In practice, however, the common tools of portfolio planning—the growth/share and market attractiveness/business position matrices—present problems in that often neither of the matrices is precisely suitable for a given individual business. This article makes use of modifications of the growth/share and market attractiveness/business position matrices in order to make them more operational. The authors believe that a step-by-step ‘shirt-sleeve’ approach to portfolio planning can make this type of analysis accessible and invaluable to a small diversified firm, as well as providing insights to larger corporations with formal planning departments.     

基于次梯度投影的泛投资组合选择策略

在线投资组合选择(online portfolio selection)问题是当前量化投资领域一个重要的研究问题.近些年来,可投资标的的爆炸式增长急需能够有效计算的投资组合选择策略,而现有高绩效算法大多具有指数级或多项式级的时间复杂度,不利于在实际中应用.由此,本文提出了一种基于次梯度投影的泛投资组合选择策略SGP.将次梯度投影的思想应用到资产组合构建的过程中,得到策略的再平衡规则.理论上,本文分析了次梯度投影算法的竞争性能,证明了该策略是一个泛投资组合选择策略;并发现该算法具有线性时间复杂度.实证上,验证了SGP策略在美国与中国市场的表现.结果表明,SGP策略能够实现和最新的泛投资组合选择策略相当的收益率,而算法运行时间短于现有策略.参数敏感性分析表明SGP策略对参数选择不敏感;交易成本敏感性分析表明SGP策略能够承受合理的交易成本.     

A fundamental approach to strategy development

The problem of developing sound business strategy is probably more difficult now than it has been at any time since the war. In the midst of conflicting pressures of inflation, recession, unemployment, business failures, and social and political upheaval, today's businessman faces an environment which is both unfamiliar and uncertain. The lack of predictability concerning economic affairs can make it seem impossible to plan effectively for the future. Yet without sound strategy today, corporate survival itself may be called into question. What should be done?In this, the first of two articles, the author suggests that the key to strategy development now is to focus more than ever before on ‘fundamentals’. For the individual business, market share appears to be paramount, as is shown by the ‘experience curve effect’, a concept developed by the Boston Consulting Group in the course of its international work in advising companies on corporate strategy problems. Relative competitive position thus becomes the required simple but fundamental strategic goal. However, the quest for a superior market share must take place within the confines of an appropriately defined strategic business segment.In a further article in the February 1977 issue of LRP the author will go on to expand these conclusions concerning individual businesses, considering their implications for the sound development of strategy for the multi-business company.     

A practical approach to strategy development

This article deals with methodology, i.e. the principles of laying out effective methods for strategy development. It does not describe the multitude of relevant methods in detail but presents them in context, i.e. inasmuch as they are interconnected.     

考虑组合预测股价的泛证券投资组合选择策略北大核心CSCD

Online portfolio selection is regarded as an important research issue in the field of quantitative finance, which often aims to maximize returns or risk-adjusted returns. Mean-variance model, a classic portfolio model, assumes that the returns on assets obey a certain probability distribution, which characterizes the return and risk by calculating the mean value and covariance matrix of the portfolio, respectively. However, it is difficult to accurately obtain the future return or return distribution of assets, and the only information that can be accurately grasped is historical price data. Therefore, some scholars try to use only historical information to construct portfolio strategy, so they pay more and more attention to online portfolio selection problem. The so-called “online” means that when making decisions in the current period, the updated investment proportion only depends on the historical data obtained up to the beginning of the current investment, and the cycle is carried out until the end of the whole investment. Stock price prediction based on past information is one of the key problems of online portfolio selection without statistical assumption. In this paper, historical price data are used to predict the stock prices, and then a new online portfolio selection strategy is constructed. In the first part of this paper, we design a new online portfolio selection strategy based on the predicted stock prices with the goal of maximizing expected returns. First of all, in order to minimize the influence of market outliers or white noise, we adopt multiperiod historical price information to predict the stock prices for the next period. Secondly, in order to reduce the prediction bias caused by a single prediction model, the exponential smoothing method and L1-median estimation method are combined to construct a combination forecasting model. Then, the stock estimator can be obtained based on the above-mentioned combination forecasting model. Finally, a new online portfolio selection strategy named Combination Forecasting for Exponential Gradient (CFEG) is proposed by taking the maximization of expected return as the goal and adding a penalty term into the objective function to reduce the transaction costs caused by each transaction adjustment. In the second part, the competitive ratio analysis is adopted to analyze the competitive performance of the proposed strategy theoretically, and the Best Constant Rebalanced Portfolios (BCRP) strategy is regarded as a straw man. After a series of derivations, it is proven that the average logarithmic growth rate of CFEG strategy is asymptotically consistent with that of the BCRP strategy, namely, the proposed strategy CFEG is a universal strategy. In the third part, numerical examples are conducted to test the performance of the proposed strategy in terms of final cumulative wealth, statistical t-test, Sharpe ratio, Calmar ratio, transaction cost sensitivity, and other parameter sensitivities. It is necessary to test the performance of our proposed CFEG strategy. Therefore, this paper further demonstrates the performance of CFEG through numerical experiments related to 8 real stock market datasets in China and the United States. First of all, the most important indicator to judge the performance of a strategy is its final cumulative wealth. We compare the final cumulative wealth between the CFEG strategy with 3 benchmark strategies and 6 related online strategies, and compare the difference of the average logarithmic growth rate between CFEG strategy and BCRP strategy. On 8 datasets, the final cumulative wealth of CFEG strategy is stably higher than that of all online strategies, and the difference of the average logarithmic growth rate between CFEG and BCRP is almost zero. The CFEG strategy has a good performance on the whole, and the p-value is very small on each dataset in the statistical t-test. Secondly, the Sharpe ratio and Calmar ratio of CFEG strategy are compared with other strategies. The results show that CFEG strategy can better balance the returns and risks, and obtain higher risk-adjusted returns. Since the transaction costs are an important realistic constraint, the sensitivity analysis of the transaction cost rate of CFEG strategy is carried out subsequently. Meanwhile, 4 strategies are also selected for the purpose of comparison. The results show that CFEG strategy can withstand reasonable transaction costs and still obtain high returns. Finally, we conduct the sensitivity analyses of 3 parameters included in the design of CFEG strategy. The results show that the proposed CFEG strategy is stable and insensitive to parameter selection. Although the best parameter values are not selected, the CFEG strategy maintains excellent performance. Therefore, effective parameters can be selected easily in practical applications. In conclusion, the proposed strategy CFEG is suitable for investors to make investment decisions effectively and efficiently. The CFEG strategy is able to update the investment proportion in time without the future stock price information, so as to achieve the goal of maximizing returns, and provide some guidance for online investors. © (2023). All Rights Reserved.     

兼并效应与产品覆盖策略

在行业寡头垄断竞争中, 引入产品覆盖策略竞争的变量, 把企业兼并时的竞争假定为两 个阶段两种变量: 先是产品覆盖策略竞争, 后是产品产量竞争, 并设计了一个描述这种兼并竞 争的模型. 在此基础上, 分析了参与和未参与兼并的企业的产品覆盖策略变化对各企业利润和 价格的影响, 在一定程度上解释了兼并悖论. 我们赞成适度的兼并控制政策, 但在经济萧条时 期可适当放宽.     

基于Copula-SV-GPD模型的投资组合风险度量

对于多元金融资产组合,针对资产收益的厚尾性、波动的异方差性及资产间的非线性相关结构等特征,采用SV-t模型与极值理论结合刻画单个资产收益的波动性及尾部分布特征,应用Copula函数处理多元资产间的相关性,并结合Monte Carlo模拟对投资组合进行风险测度.通过对华安创新基金的实证分析结果表明,基于SV-GPD的边缘分布模型能有效地刻画金融资产收益时序并较为精确地处理资产收益尾部的异常变化,相比其他风险度量模型具有更好的优越性,基于Copula-SV-GPD模型的多元资产组合对风险测度能力更强,能有效地管理投资风险.     

结合资产配置策略测算多期收益保证价值

投资机构能够采取某种资产配置策略,改变由收益保证所引致的期末偿付能力不足风险,并根据风险与价值对等的原则,进而改变收益保证的价值.但是,现有文献在测算收益保证价值时并没有考虑资产配置策略.针对现有文献的不足,在一种新的收益保证形式下,提出了结合资产配置策略测算收益保证价值的新方法,然后以固定组合(CM)、生命周期(DL...     

A robust approach to the share-of-choice product design problem

A critical issue when solving the share-of-choice product design problem is the reliability of the optimal solution in the presence of partworth uncertainty. Existing approaches use point estimates of an individual's partworth utilities as input to the product optimization stage, ignoring within-person variability in estimates. Post-optimality sensitivity analysis is occasionally performed to assess the degree to which a solution is negatively impacted by partworth uncertainty. We propose a robust optimization model that explicitly captures variation in partworth estimates during the optimization process. Using a large, commercial dataset, we benchmark our model's performance against its deterministic counterpart. We also present inferential theory to guide the selection of model parameters controlled by the analyst. Results reveal that the new approach produces robust solutions in the face of measurement error. Out-of-sample coverage for individuals drawn from the target population is significantly higher than corresponding solutions from published methods.     

Multi-horizon Markowitz portfolio performance appraisals: A general approach

This article extends the analysis of multi-horizon mean-variance portfolio analysis in the Morey and Morey [Mutual fund performance appraisals: a multi-horizon perspective with endogenous benchmarking. Omega 1999;27:241–58] article in several ways. First, instead of either proportionally contracting risk dimensions or proportionally expanding return dimensions, a more general efficiency measure simultaneously attempts to reduce risk and to expand return over all time periods. Second, a duality relation is established between this generalized multi-horizon efficiency measure and an indirect mean-variance utility function, underscoring the natural interpretation of this generalized efficiency measure in terms of investor's preferences. Furthermore, the need to properly apply time discounting in multi-horizon mean-variance portfolio problems is argued for. An empirical illustration based on the original mutual fund data set in Morey and Morey [Mutual fund performance appraisals: a multi-horizon perspective with endogenous benchmarking. Omega 1999;27:241–58] is added to contrast the new and the original approaches.     

Strategic approach to the development of a superior product.

This article describes an innovative approach to the design and delivery of health care services; a brief summary of the underlying rationale of the approach; a comparison of the traditional health care delivery system with the new, extended product line (EPL) approach; and an evaluation of the extended product line process. Information regarding the extended product line will be presented as a case study, describing one hospital's experience with the development of a cardiac extended product line.     

多品种集约生产计划问题的模糊方法

提出具有模糊需求量和模糊能力约束以及资本水平约束的多品种类集约生产计划问题 的模糊优化模型及模糊解方法. 通过对模糊需求量和模糊等式的描述,提出了模糊需求环境下 生产- 库存平衡方程的两种等价的描述方法, 并给出了模糊等式的实用解释. 建立了具有模 糊需求量和模糊能力约束集约生产计划问题的优化模型FMAPP ,并给出了求解模型的参数规 划方法.     

Overviewing the transition of Markowitz bi-criterion portfolio selection to tri-criterion portfolio selection

Over 60 years ago, Markowitz introduced the mean-variance efficient frontier to finance. While mean-variance is still the predominant model in portfolio selection, it has endured many criticisms. One serious one is that it does not allow for additional criteria. The difficulty is that the efficient frontier becomes a surface. With it now possible to compute such a surface, we provide an overview on how Markowitz’s risk-return (bi-criterion) portfolio selection can be extended to tri-criterion portfolio selection. With a focus on the geometry of the extension, many graphs are used to illustrate.     

Contextual influences on international subsidiaries' product technology strategy

We seek to test a broad range of factors that influence the technology sourcing decision of international subsidiaries in acquiring product technology from outside the firm (i.e., outsourcing) versus internal development. A regression model, used to analyze data from 187 international subsidiaries in six industries and with parents based in 14 countries, identifies the environmental, strategic, configurational, and resource endowment factors that influence the technology sourcing decision. Specifically, the level of product dynamism in the subsidiary's industry and the distance between the subsidiary's primary marketing and R&D operations are associated with a greater reliance on outsourcing. A differentiation goal, a low-cost goal, along with the level of the subsidiary's human and financial resources are associated with a greater reliance on internal development.     

网络外部性、产品差异化与企业技术控制策略

研究具有网络外部性特征的市场中,拥有专有技术的在位厂商对其技术的授权动机.研究结果表明,在消费者对产品未来市场规模的预期为随机变量的假设下,如果网络外部性强度较弱或者产品差异化较强,专有技术厂商将开放技术,引入竞争性厂商,从而获得比独享技术更高的利润;反之,如果网络外部性强度较强或者产品差异化较弱,专有技术厂商将独享技术,从而成为行业垄断者。     

Ascribing materiality and agency to strategy in interaction: A language-based approach to the material agency of strategy

Adding to the existent research on strategy as discourse and practice, this paper develops a language-based approach to viewing the agency and materiality of strategy. The study draws insights from the communicative constitution of organization (CCO) approach and linguistic agency to investigate how organizational members ascribe materiality and performative agency to strategy in their talk-in-interaction. The data consist of 14 video-recorded dyadic manager-to-manager conversations from one private and one public Finnish organization. The findings highlight how strategy is habitually spoken of as a material concrete entity and as a nonhuman agent that makes a difference in the course of described actions. The findings thus suggest that the performative position of strategy has been encoded in language and its use, which further suggests that object-like concreteness and agentivity are key elements of the organizational strategy discourse.     

The business portfolio approach—Where it falls down in practice

During the past decade the SBU (or portfolio) concept has enjoyed widespread popularity as a basis for corporate-wide strategic planning systems within large, diversified firms. This article discusses the implementation of such systems on the basis of 3 years of clinical and small sample research. A ‘basic model’ of implementation is used as a basis for comparison to progressive practice as observed in a sample of 13 firms. Furthermore, a new conceptual perspective for the portfolio concept is developed as a complement to the observed approach to implementation.