Shortability and asset pricing model: Evidence from the Hong Kong stock market

This study explores how the violation of free short selling assumption affects the performance of CAPM and the Fama-French three-factor model, as existing studies show that short-sales constraints affect asset pricing of the stocks. Using data from the Hong Kong Stock Market which has unique regulations on short selling, we conduct both time-series and cross-sectional regression analyses to evaluate the performance of the two models under the short-sales-constraints and the no-constraints market environment. The two models perform much worse in the former environment than in the latter, indicating a significant impact of the short sales constraints on the explanatory power of the models. We then augment the two models with a shortability-mimicking factor. Our results show that the factor has a significant power in explaining both time-series and cross-sectional variation in the size-B/M portfolio returns. The addition of the factor to the two models considerably increases their overall performance.     

A Note on International Portfolio Diversification with Short Selling

In this paper, the diversification benefits of using stock index futures are examined. Empirical evidence shows that traditional diversification in international equity markets does not produce a risk adjusted performance superior to the US market. An explanation for this result is that restrictions on short selling prohibit the best allocation of resources when overseas stock markets are riskier and have worse returns. However, when such restrictions are eased for short selling in index futures markets, investors are enabled to both allocate their investments more efficiently and to construct a superior portfolio.     

Portfolio selection under institutional procedures for short selling: Normative and market-equilibrium considerations

In view of the acceptance of short selling of stocks as an investment tool in the portfolio context by a growing number of institutional investors in recent years, the present study considers both normative and market-equilibrium aspects of portfolio selection with short selling. Under the full-information covariance structure of security returns, the study accurately captures institutional procedures for short selling without sacrificing analytical tractability. While short selling enhances the portfolio's risk-return trade-off from a normative perspective, the equilibrium analysis reveals that there is a continuum of market-clearing prices within two boundaries for each security. Economic implications of the equilibrium pricing relationship are also explored in the study.     

Exploring the benefits of using stock characteristics in optimal portfolio strategies

I examine the benefits of using stock characteristics to model optimal portfolio weights in stock selection strategies using the characteristic portfolio approach of Brandt, Santa-Clara, and Valkanov. [2009. “Parametric Portfolio Policies: Exploiting Characteristics in the Cross-section of Equity Returns.” Review of Financial Studies 22: 3411–3447]. I find that there are significant out-of-sample performance benefits in using characteristics in stock selection strategies even after adjusting for trading costs, when investors can invest in the largest 350 UK stocks. Imposing short selling restrictions on the characteristic portfolio strategy leads to more consistent performance. The performance benefits are concentrated in the earlier part of the sample period and have disappeared in recent years. I find that there no performance benefits in using stock characteristics when using random subsets of the largest 350 stocks.     

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.     

SHORT SELLING AND MISPRICINGS WHEN FUNDAMENTALS ARE KNOWN: EVIDENCE FROM NYSE‐TRADED CLOSED‐END FUNDS

The larger a closed‐end fund's premium over its portfolio value, the more intensely it is sold short. This behavior should reduce mispricings. However, short selling affects neither the observed rate at which premia revert to fundamental values nor the rate of return on a fund's shares. This apparent contradiction can be explained as follows: short selling does reduce prices, but the effect is impounded into prices by the time short positions are tabulated by the NYSE each month. Consequently, the monthly short selling data do not predict future price movements.     

Industry momentum strategies and autocorrelations in stock returns

In this study, we examine the sources of profits to momentum strategies of buying past winner industry portfolios and selling short past loser industry portfolios. We decompose the profit into (1) own-autocovariances in industry portfolio returns, (2) cross-autocovariances among industry portfolio returns, and (3) cross-sectional dispersion in mean portfolio returns. Our empirical results show that the industry momentum effect is mainly driven by the own-autocorrelation in industry portfolio returns, not by return cross-autocorrelations or by cross-sectional differences in mean returns. Indeed, the industry momentum strategy generates statistically significant profits only when own-autocorrelations are positive and statistically significant. The evidence is consistent with several behavioral models (e.g. Journal of Financial Economics 45 (1998) 307; Journal of Finance 53 (1998) 1839; Journal of Finance 54 (1999) 2143) that suggest positive own-autocorrelations in stock returns and hence the price momentum.     

The structure and management of dual purpose funds

Dual fund shares allow individuals to satisfy their divergent preferences for the ordinary income and the capital gains components of return. Institutional restrictions on short selling are shown to permit discounts on dual funds to fluctuate within wide bounds. However, these fluctuations are shown to be consistent with informational efficiency. The average discount is shown to have a contemporaneous association with net redemptions of diversified open-end funds. It is shown that the high turnover of dual fund portfolios is not warranted by their portfolio performance and causes redistributions of wealth between income and capital shareholders.     

Trading strategies based on past returns: evidence from Germany

Among the various strategies studied in this paper, only momentum investing appears to earn persistently nonzero returns: From 1965 to 2014, the classical momentum strategy based on performance over the previous 2–12 months earned an average return of 1.57% per month (excluding microcap stocks and value-weighted returns). In the most recent 10-year period, this return was even larger—2.27%—which is much larger than in the USA. However, profitability net of transaction costs is weak because the strategy involves trading in disproportionately small stocks with high transaction costs, something that is particularly true for the loser portfolio. A strategy that concentrates only on the winner portfolio and thus avoids potential problems associated with (short) selling the costly loser portfolio appears to earn strong and persistently abnormal profits, even after transaction costs.     

卖空限制与收益可预测性——A股融资融券制度的证据

基于A股市场融资和融券余额的巨大差距,本文拓展了Hong et al.(2016)的理论模型,在融券端和融资端分别找到了影响股票收益率的变量:融券比率(融券余额/流通市值)和融资回补天数(融资比率/日均换手率)。进一步,本文利用组合价差法和Fama-MacBeth横截面回归法,实证检验了A股市场中融券比率与融资回补天数解释和预测股票收益率的能力。实证结果表明,在存在融券限制条件下,融券比率相比融券回补天数(融券比率/日均换手率)能更好地代表套利者对股票价格高估程度的看法,根据融券比率构建的等权重多空组合能带来月均1.58%的显著收益;而由于融资约束相对较少,融资回补天数相比融资比率(融资余额/流通市值)能更好地代表套利者对股票价格低估程度的看法,根据融资回补天数构建的等权重多空组合能带来月均1.28%的显著收益。实证结果与本文存在融券数量限制下的理论模型相符,且该收益率不能被多因子模型和常规股票特征所解释。     

Can Investors Profit from the Prophets? Security Analyst Recommendations and Stock Returns

We document that purchasing (selling short) stocks with the most (least) favorable consensus recommendations, in conjunction with daily portfolio rebalancing and a timely response to recommendation changes, yield annual abnormal gross returns greater than four percent. Less frequent portfolio rebalancing or a delay in reacting to recommendation changes diminishes these returns; however, they remain significant for the least favorably rated stocks. We also show that high trading levels are required to capture the excess returns generated by the strategies analyzed, entailing substantial transactions costs and leading to abnormal net returns for these strategies that are not reliably greater than zero.     

卖空限制与收益可预测性——A股融资融券制度的证据

基于A股市场融资和融券余额的巨大差距,本文拓展了Hong et al.(2016)的理论模型,在融券端和融资端分别找到了影响股票收益率的变量:融券比率(融券余额/流通市值)和融资回补天数(融资比率/日均换手率)。进一步,本文利用组合价差法和Fama-MacBeth横截面回归法,实证检验了A股市场中融券比率与融资回补天数解释和预测股票收益率的能力。实证结果表明,在存在融券限制条件下,融券比率相比融券回补天数(融券比率/日均换手率)能更好地代表套利者对股票价格高估程度的看法,根据融券比率构建的等权重多空组合能带来月均1.58%的显著收益;而由于融资约束相对较少,融资回补天数相比融资比率(融资余额/流通市值)能更好地代表套利者对股票价格低估程度的看法,根据融资回补天数构建的等权重多空组合能带来月均1.28%的显著收益。实证结果与本文存在融券数量限制下的理论模型相符,且该收益率不能被多因子模型和常规股票特征所解释。     

An empirical examination of the benefits of international diversification

We examine the benefits of international portfolio diversification for U.K. investors between January 1985 and December 2000 using the approach of Wang [Wang, Z., 1998. Efficiency loss and constraints on portfolio holdings. Journal of Financial Economics 48, 359–375] and Li et al. [Li, K., Sarkar, A., Wang, Z., 2003. Diversification benefits of emerging markets subject to portfolio constraints. Journal of Empirical Finance 10, 57–80]. We find significant increases in the Sharpe [Sharpe, W.F., 1966. Mutual fund performance. Journal of Business 39, 119–138] and certainty equivalent return (CER) performance in moving from a domestic strategy to an international strategy that includes either global industry or country equity portfolios, even in the presence of short selling restrictions. We also find significant diversification benefits using U.K. unit trusts with international equity objectives. However, U.K. international unit trusts do not capture all the diversification benefits provided by either global industry or country equity portfolios.     

Tax management strategies with multiple risky assets

We study the consumption-portfolio problem in a setting with capital gain taxes and multiple risky stocks to understand how short selling influences portfolio choice with a shorting-the-box restriction. Our analysis uncovers a novel trading flexibility strategy whereby, to minimize future tax-induced trading costs, the investor optimally shorts one of the stocks (or equivalently, buys put options) even when no stock has an embedded gain. Alternatively, an imperfect form of shorting the box can reduce aggregate equity exposure ex post. Given these two short selling strategies, it is common for an unconstrained investor to short some equity while a constrained investor holds a positive investment in all stocks. With no shorting, the benefit of trading separately in multiple stocks is not economically significant.     

A note on market-neutral portfolio selection

Long–short equity strategies allow investors to benefit potentially from both undervalued and overvalued securities. The present study develops a normative portfolio model under the practical conditions that a market-neutral strategy entails. The offsetting long and short equity holdings are established jointly and without any constraints by the underlying market index. While accurately capturing institutional procedures for short selling, the model contains the analytical and economic properties as required for a ranking approach to filter out any undesirable securities under consideration. In view of its practical features, the analysis should be of interest to practitioners for assisting their long–short investment decisions.     

Short selling in initial public offerings

Short sale constraints in the aftermarket of initial public offerings (IPOs) are often used to explain short-term underpricing that is subsequently reversed. This paper shows that short selling is integral to aftermarket trading and is higher in IPOs with greater underpricing. Perceived restrictions on borrowing shares are not systematically circumvented by “naked” short selling. Short sellers, on average, do not appear to earn abnormal profits in the near term and our findings are not driven by market makers. Short selling in IPOs is not as constrained as suggested by the literature, implying that other factors may be responsible for underpricing.     

Momentum profits in the Australian equity market: A matched firm approach

This paper examines momentum trading strategies within the Australian equity market over the period 1990 to 2007, inclusive. We analyse excess returns employing both Jegadeesh and Titman's (Jegadeesh, N., Titman, S., 1993. “Returns to buying winners and selling losers: implications for stock market efficiency”. The Journal of Finance, 48:65–91) zero cost investment portfolio approach and a matched control firm approach. We also allow for short sale restrictions, liquidity constraints and transaction costs in the form of bid-ask spreads. Testing reveals that both the Jegadeesh and Titman (Jegadeesh, N., and Titman, S. (1993). “Returns to buying winners and selling losers: implications for stock market efficiency”. The Journal of Finance, 48:65–91.) zero cost investment portfolio approach and the matched control firm approach yield excess profits. While the implementation of short sale restraints increases momentum profitability, the subsequent inclusion of bid-ask spreads results in a reduction in these gains. Further, we find that executing a momentum strategy in Australia results in statistically significant dollar profits.     

Short Selling and Firm Operating Performance

While it is well known that short selling predicts future negative stock price performance, it has not been established whether short selling predicts future negative operating performance. We find that firms in the top decile of increases in short interest (an increase of about four percentage points) experience a 21% subsequent decline in operating performance relative to matched control firms. The greater the increase in short interest, the larger the decline in operating performance. The results are robust to alternative performance measures and to sample splits based on firm size. These results suggest that short interest may reflect private information about firm fundamentals rather than other factors that may drive stock price changes.     

Financial turbulence,systemic risk and the predictability of stock market volatility

This paper adds a novel perspective to the literature by exploring the predictive performance of two relatively unexplored indicators of financial conditions, i.e. financial turbulence and systemic risk, over stock market volatility using a sample of seven emerging and advanced economies. The two financial indicators that we utilize in our predictive setting provide a unique perspective on market conditions, as they relate directly to portfolio performance metrics from both volatility and co-movement perspectives and, unlike other macro-financial indicators of uncertainty, or risk, can be integrated into diversification models within forecasting and portfolio design settings. Since the data for the two predictors are available at a weekly frequency, and our focus is to produce forecasts at the daily frequency, we use the generalized autoregressive conditional heteroskedasticity-mixed data sampling (GARCH-MIDAS) approach. The results suggest that incorporating the two financial indicators (singly and jointly) indeed improves the out-of-sample predictive performance of stock market volatility models over both the short and long horizons. We observe that the financial turbulence indicator that captures asset price deviations from historical patterns does a better job when it comes to the out-of-sample prediction of future returns compared with the measure of systemic risk, captured by the absorption ratio. The outperformance of the financial turbulence indicator implies that unusual deviations in not only asset returns, but also in correlation patterns play a role in the persistence of return volatility. Overall, the findings provide an interesting opening for portfolio design purposes, in that financial indicators, which are directly associated with portfolio diversification performance metrics, can also be utilized for forecasting purposes, with significant implications for dynamic portfolio allocation strategies.     

Implications of Short Selling for Corporate Finance

Corporate managers often view short sellers as market manipulators whose actions drive their company's stock price below intrinsic value. But recent academic research suggests that some short sellers are effective in processing publicly available information and that their short selling may provide useful information to market participants. This article summarizes the authors’ own published research, which provides evidence of informed short selling by linking it to changes in corporate fundamentals. More specifically, the authors’ findings indicate that increases in short interest are reliable indicators of an economically (as well as statistically) significant decline in a company's operating performance over the following three years. And when examining changes in short interest around announcements of seasoned equity offerings, the authors also find a negative relation between an increase in short interest and future operating performance. In addition, they find that the greater the increase in short interest in the period leading up to the SEO announcement, the more negative is the stock‐price response to the announcement itself. The authors’ findings suggest that corporate managers can benefit from monitoring the short‐selling activity in their company's stock. Short‐selling data can be used to reassess corporate strategy or rethink major corporate decisions that have been announced but not carried out, and take preemptive actions to forestall impending future declines in performance and so preserve value.