THE ECONOMIC SIGNIFICANCE OF CONDITIONING INFORMATION ON PORTFOLIO EFFICIENCY IN THE PRESENCE OF COSTLY SHORT‐SELLING

The economic significance of conditioning information in the presence of costly short‐selling is investigated. Using a compact testing framework, results demonstrate that fixed‐weight stock‐bond portfolios appear inefficient with respect to stock‐bond portfolios with weights determined by extant predictors. However, this result is highly dependent on ex ante knowledge of the predictor set and the ability to short‐sell at low cost. In the absence of such conditions, fixed‐weight stock‐bond portfolios appear efficient with respect to conditioning information.     

Indexing mergers and acquisitions

We measure the efficiency of mergers and acquisitions by putting forward an index (the ‘M&A Index’) based on stochastic frontier analysis. The M&A Index is calculated for each takeover deal and is standardized between 0 and 1. An acquisition with a higher index encompasses higher efficiency. We find that takeover bids with higher M&A Indices are more likely to succeed. Moreover, the M&A Index shows a strong and positive relation with the acquirers’ post-acquisition stock performance in the short run and operating performance in the long run. After constructing three portfolios under a buy-and-hold strategy, we find that efficient portfolios with the highest indices earn higher equity returns and monthly alphas than inefficient portfolios with the lowest indices. Overall, our findings indicate that the M&A Index is positively associated with merger outcomes for acquirers.     

Systematic Risk and Empirical Research

We show here that risky asset returns generating processes stated in terms of factors which include both accounting and non-accounting based measures of risk (e.g. book to market ratios) imply, under fairly standard regularity conditions, that the Sharpe-Lintner-Black asset pricing model beta is a 'sufficient' statistic in the sense that it captures all important attributes of the returns generating process in a single number. We then derive the parametric relationship between betas based on inefficient index portfolios and betas based on the market or tangency portfolio. We demonstrate that the relationship between risky asset expected returns and betas computed on the basis of inefficient index portfolios is both consistent with the predictions of the Capital Asset Pricing Model and the multi-factor asset pricing models of Fama and French (1992, 1993, 1995 and 1996). The 'trick' is to realise that inefficient index portfolios are composed of the market portfolio and a collection of inefficient but self financing 'kernel' or 'arbitrage' portfolios. It then follows that there is a perfect linear cross sectional relationship between risky asset expected returns, betas based on inefficient index portfolios and the arbitrage portfolios. Hence, if we happen to stumble across variables that span the same subspace as the vectors representing the arbitrage portfolios, it is easy to create the illusion that risky asset expected returns depend on variables other than 'beta'.     

Efficient portfolios when housing needs change over the life cycle

We address the issue of the efficiency of household portfolios in the presence of housing risk. We treat housing stock as an asset and rents as a stochastic liability stream: over the life cycle, households can be short or long in their net-housing position. Efficient financial portfolios are the sum of a standard Markowitz portfolio and a housing risk hedge term that multiplies net housing wealth. Our empirical results show that net housing plays a key role in determining which household portfolios are inefficient. The largest proportion of inefficient portfolios obtains among those with positive net housing, who should invest more in stocks.     

The econometrics of efficient portfolios

It is well known that the standard mean variance approach can be inappropriate when return distributions feature skewness, fat tails or multimodes. This is typically the situation for portfolios including derivatives. In this case, it can be necessary to come back to the basic expected utility approach. In this paper, an efficient portfolio maximizes the expected utility of future wealth. This paper presents an analysis of the efficiency frontier, formed by a set of efficient portfolios corresponding to a parameterized class of utility functions. First, we discuss the estimation of an efficient portfolio and introduce several tests of the efficiency hypothesis, depending on what is known about the utility function and the budget level. Next we analyse the shape of the frontier and develop a procedure for testing the separability of the efficiency frontier into K independent funds. The inference is semi-nonparametric because the return distribution is left unspecified. We illustrate our approach by an application to portfolios including derivatives.     

Investment Policy Implications of the Capital Asset Pricing Model

The results of previous generalized Security Market Line (SML) tests of the Mean Variance (MV) and Linear Risk Tolerance (LRT) Capital Asset Pricing Models indicate that the models are empirically identical. A very widely accepted, but technically incorrect, explanation for the results is that with normal return distributions all expected utility maximizing riskaverse investors will pick MV portfolios. The paper shows that the generalized SML tests cannot distinguish between the MV model and a much wider variety of power utility LRT models than has previously been entertained. On the other hand, with approximately normal, or real world, return distributions the investment policies of the various models are shown to be different from each other, and from the MV policy in particular. To the extent the results of the portfolio selection calculations are robust, the results of, and implications drawn from, the tests of the macro pricing relations are not based on firm micro foundations.     

The Effect of Bankruptcy Protection on Investment: Chapter 11 as a Screening Device

Asymmetric information and conflicts of interest between equity and debt holders can force a distressed but efficient firm to liquidate and may enable a distressed inefficient firm to continue. In the extreme, if it is costless for an inefficient firm to mimic an efficient firm in a debt restructuring, efficient and inefficient firms are equally likely to continue or liquidate. This article shows that Chapter 11 procedures impose costs on inefficient firms that would otherwise mimic efficient firms. This separation induces voluntary filing for bankruptcy by inefficient firms and consequently enables efficient firms to continue when they would otherwise be liquidated.     

Thematic portfolio optimization: challenging the core satellite approach

In recent years, thematic exchange-traded funds (ETF) have increased in economic significance. Investors in thematic ETFs have more than just financial objectives and gain a non-monetary added value from a thematic portion in their portfolios. Therefore, traditional portfolio optimization models which target only financial criteria cannot suit these investors’ needs anymore. Nevertheless, to account for their thematic interests, investors adapt a core satellite strategy in which conventional core portfolios and thematic satellite portfolios are combined. Thus, these portfolios are separately optimized without further considering inter-portfolio correlation effects. Since modern portfolio theory has originally been established to, inter alia, optimize these correlation effects, portfolios can only be efficient by chance. Therefore, this study targets the correlation effects between conventional and thematic portfolios and uses a tri-criterion thematic portfolio optimization model as an overall framework. Throughout a two-part analysis with tradable ETFs and a simulation with 250,000 draws and 1,750,000 portfolio optimizations performed, the status quo is compared to the tri-criterion model. Quantifying the suboptimality, simulation results show a mean portfolio improvement of 6.23% measured as relative yield enhancement. Further, our analysis concludes that the more narrowly a theme is defined and the more particular it is, relative yield enhancements can increase up to 46.88%.

     

Empirical Tests for Stochastic Dominance Efficiency

We derive empirical tests for the stochastic dominance efficiency of a given portfolio with respect to all possible portfolios constructed from a set of assets. The tests can be computed using straightforward linear programming. Bootstrapping techniques and asymptotic distribution theory can approximate the sampling properties of the test results and allow for statistical inference. Our results could provide a stimulus to the further proliferation of stochastic dominance for the problem of portfolio selection and evaluation. Using our tests, the Fama and French market portfolio is significantly inefficient relative to benchmark portfolios formed on market capitalization and book‐to‐market equity ratio.     

Orthogonal Frontiers and Alternative Mean-Variance Efficiency Tests

This paper catalogues properties of minimum norm orthogonal portfolios: portfolios which minimize a quadratic objective function and have returns uncorrelated with those of a candidate portfolio that is not mean-variance efficient. The analysis shows that the dollar versions of these portfolios correspond to estimators of zero beta rates based on alternative statistical criteria and grouping procedures while costless orthogonal portfolios represent candidate mean-variance efficiency tests. It also develops inference procedures for zero and unit net investment portfolios of individual securities (instead of grouped portfolios) that have zero expected betas. The resulting mean-variance efficiency tests are reasonably insensitive to the underlying statistical assumptions.     

Downside risk and asset pricing

We analyze if the value-weighted stock market portfolio is stochastic dominance (SD) efficient relative to benchmark portfolios formed on size, value, and momentum. In the process, we also develop several methodological improvements to the existing tests for SD efficiency. Interestingly, the market portfolio seems third-order SD (TSD) efficient relative to all benchmark sets. By contrast, the market portfolio is inefficient if we replace the TSD criterion with the traditional mean–variance criterion. Combined these results suggest that the mean–variance inefficiency of the market portfolio is caused by the omission of return moments other than variance. Especially downside risk seems to be important for explaining the high average returns of small/value/winner stocks.     

Efficiency in private banking: evidence from Switzerland and Liechtenstein

This paper examines the technical efficiency of private banking institutions in Switzerland and Liechtenstein by means of data envelopment analysis (DEA). The average wealth manager’s relative inefficiency level is found to exceed 20% in most of the years between 2003–2007. Results also reveal that the average bank is well above its efficient scale of operations. Private banks from Liechtenstein fare better than their Swiss counterparts. Specialization and investment performance appear to be important factors in distinguishing efficient from inefficient institutions. The significance of these bank features, however, can be traced back to the worst performers in the sample. Bank size, capital strength, asset composition, network size, and ownership do not help answer the question of what constitutes an efficient wealth manager.     

Positively Weighted Portfolios on the Minimum-Variance Frontier

Duality theory is employed to provide necessary and sufficient conditions for portfolios on the minimum-variance frontier to have positive investment proportions in all assets. These conditions involve the feasibility of portfolios that have non-negative correlation with all assets and positive correlation with at least one. Using these results, several “qualitative” results concerning the signs of investment proportions in efficient portfolios are proved. It is argued that the conditions that ensure all-positive weights in efficient portfolios are intuitively compelling and are not unique to the CAPM. With large numbers of assets, however, the signs of weights in minimum-variance portfolios can be very sensitive to slight departures from these conditions due to, for example, sampling error.     

REGULATORY INFLUENCES ON PORTFOLIO PERFORMANCE: SHORT SELLING AND REGULATION T

Several models are developed to examine the portfolio effect of short selling. Three things are demonstrated in this study. First, that for many assets, short selling is a useful strategy for reducing risk when constructing mean-variance efficient portfolios. Second, Regulation T can be used in combination with short selling to further improve expected portfolio performance. Third, the performance of the suggested models is superior to previously suggested allocation models. Ex ante and ex post tests are conducted to arrive at the above conclusions.     

Estimating the Value of Employee Stock Option Portfolios and Their Sensitivities to Price and Volatility

The costs associated with compiling data on employee stock option portfolios is a substantial obstacle in investigating the impact of stock options on managerial incentives, accounting choice, financing decisions, and the valuation of equity. We present an accurate method of estimating option portfolio value and the sensitivities of option portfolio value to stock price and stock-return volatility that is easily implemented using data from only the current year's proxy statement or annual report. This method can be applied to either executive stock option portfolios or to firm-wide option plans. In broad samples of actual and simulated CEO option portfolios, we show that these proxies capture more than 99% of the variation in option portfolio value and sensitivities. Sensitivity analysis indicates that the degree of bias in these proxies varies with option portfolio characteristics, and is most severe in samples of CEOs with a large proportion of out-of-the-money options. However, the proxies' explanatory power remains above 95% in all subsamples.     

Linear programing models for portfolio optimization using a benchmark

We consider the problem of constructing a perturbed portfolio by utilizing a benchmark portfolio. We propose two computationally efficient portfolio optimization models, the mean-absolute deviation risk and the Dantzig-type, which can be solved using linear programing. These portfolio models push the existing benchmark toward the efficient frontier through sparse and stable asset selection. We implement these models on two benchmarks, a market index and the equally-weighted portfolio. We carry out an extensive out-of-sample analysis with 11 empirical datasets and simulated data. The proposed portfolios outperform the benchmark portfolio in various performance measures, including the mean return and Sharpe ratio.     

Market timing for the individual investor: Using the predictability of long-horizon stock returns to enhance portfolio performance

Recent research indicates that dividend yield and earnings-price ratio can partially predict long-horizon stock returns. We examine whether individual investors can successfully construct timing portfolios based on either of these variables or a measure of the expected market risk premium. The out-of-sample tests in this study require that investors rely only on information that was available at the time of the market-timing decision. Timing portfolios based on the market risk premium show the strongest ability to time the market. We present an economic rationale for the results that is consistent with efficient markets.     

Do Socially Responsible Index Investors Incur an Opportunity Cost?

We construct index‐tracking portfolios using integer programming and then compare the tracking errors and performances of portfolios formed from an unrestricted and socially screened stock universe. We find that one can construct a portfolio of socially responsible stocks that deliver market performance. Thus, the exclusion of a set of stocks from consideration does not exhaust the existence of efficient index‐tracking portfolios, especially when the exclusionary screen is for nonfinancial reasons. Our results are robust to various specifications in constructing the portfolio, for example, number of stocks included in the portfolio and weighting schemes, and robust to alternative tracking error measurement; we show that the difference induced from conducting socially responsible screen is never statistically significant.     

CAN INEFFICIENT TRADERS CREATE VALUE?

I examine the aggregate expected profit generated by informed traders of diverse ability in a competitive market. I assume that efficient traders get perfect information on asset values whereas inefficient traders get noisy information. In the presence of order size restrictions, I show that the aggregate expected profit generated by efficient and inefficient traders together can be higher than that generated by efficient traders alone. Thus, inefficient traders can create value in a constrained trading environment.