Regulatory Uncertainty and Market Liquidity: The 2008 Short Sale Ban's Impact on Equity Option Markets

We examine how the September 2008 short sale restrictions and the accompanying confusion and regulatory uncertainty impacted equity option markets. We find that the short sale ban is associated with dramatically increased bid‐ask spreads for options on banned stocks. In addition, synthetic share prices for banned stocks become significantly lower than actual share prices during the ban. We find similar results for synthetic share prices of hard‐to‐borrow stocks, suggesting that the dislocation in actual and synthetic share prices is attributable to the increased hedging costs for options on banned stocks during the short sale ban.     

Effect of the ban on short selling on market prices and volatility

We examine the effects of the short‐selling ban, imposed by Australian regulators in the wake of the global financial crisis, on the trading of financial stocks. Our findings argue against commonly stated reasons for imposing short‐sale bans. We find no evidence that short‐sale restrictions provide support for stock prices or that they reduce volatility. Moreover, stocks subject to the short‐selling ban suffered a severe degradation in market quality. Controlling for the adverse effects of the financial crisis on markets, we show that short‐selling restrictions increase intraday volatility, reduce trading activity and increase bid–ask spreads.     

Options and the Bubble

Many believe that a bubble existed in Internet stocks in the 1999 to 2000 period, and that short‐sale restrictions prevented rational investors from driving Internet stock prices to reasonable levels. In the presence of such short‐sale constraints, option and stock prices could decouple during a bubble. Using intraday options data from the peak of the Internet bubble, we find almost no evidence that synthetic stock prices diverged from actual stock prices. We also show that the general public could cheaply short synthetically using options. In summary, we find no evidence that short‐sale restrictions affected Internet stock prices.     

The impact of naked short selling on the securities lending and equity market

This paper examines the impact of naked short selling on equity markets where it is restricted to securities on an approved list. Consistent with Miller's (1977) intuition, stocks with the highest dispersion of opinions and short sale constraints are the only stocks to exhibit significant and negative abnormal returns in the post-event period. We also find slightly higher stock return volatility and a small reduction in liquidity when naked short sales are allowed. Overall, it impairs market quality (liquidity and volatility), although there appears to be some improvement in price efficiency in stocks with high short sale constraints.     

Options,Short Sales,and Market Completeness

This paper presents empirical evidence that trading in options contributes to both transactional and informational efficiency of the stock market by reducing the effect of constraints on short sales. The significantly higher average level of short interest exhibited by optionable stocks supports the argument that options facilitate short selling. We also find significant effects on option prices, related to the short interest in the underlying stock. We then present evidence that options also increase information efficiency. Earlier work, that is replicated and extended here, has suggested that short sale constraints cause stock prices to underweight negative information. Options appear to reduce that effect.     

Locals,foreigners, and multi-market trading of equities: Intraday evidence from Thailand

We study stock market orders and trades in a developing country, Thailand, where foreign ownership limits partially segment local and foreign investors into two distinct markets. Some foreigners forgo voting rights and distributions to trade on the “local board”, while some locals forgo such benefits and pay a price premium to trade on the “foreign board”. Regardless of nationality, these cross-market traders typically submit orders when liquidity is high, fill orders at relatively beneficial prices, exploit patterns in stock prices across markets, display profitable holding-period returns, and enhance price discovery. This suggests that skilled, informed trading that affects market quality does not depend on trader nationality.     

Efficiency and the Bear: Short Sales and Markets Around the World

We analyze cross‐sectional and time‐series information from 46 equity markets around the world to consider whether short sales restrictions affect the efficiency of the market and the distributional characteristics of returns to individual stocks and market indices. We find some evidence that prices incorporate negative information faster in countries where short sales are allowed and practiced. A common conjecture by regulators is that short sales restrictions can reduce the relative severity of a market panic. We find strong evidence that in markets where short selling is either prohibited or not practiced, market returns display significantly less negative skewness.     

Locals, foreigners, and multi-market trading of equities: Intraday evidence from Thailand

We study stock market orders and trades in a developing country, Thailand, where foreign ownership limits partially segment local and foreign investors into two distinct markets. Some foreigners forgo voting rights and distributions to trade on the “local board”, while some locals forgo such benefits and pay a price premium to trade on the “foreign board”. Regardless of nationality, these cross-market traders typically submit orders when liquidity is high, fill orders at relatively beneficial prices, exploit patterns in stock prices across markets, display profitable holding-period returns, and enhance price discovery. This suggests that skilled, informed trading that affects market quality does not depend on trader nationality.     

Heterogeneous Expectations,Restrictions on Short Sales,and Equilibrium Asset Prices

Under heterogeneous expectations, the mean–variance model of capital market equilibrium is employed to determine the effect restricting short sales has on equilibrium asset prices. Two equivalent markets differing only with respect to short sale restrictions are compared. It is shown that, in general, risky asset prices can either rise or fall due to short sale constraints. However, under a homogeneity of beliefs for the covariance matrix of future prices, short sale constraints will only increase risky asset prices.     

The good news in short interest

Stocks with relatively high short interest subsequently experience negative abnormal returns, but the effect can be transient and of debatable economic significance. In contrast, relatively heavily traded stocks with low short interest experience both statistically and economically significant positive abnormal returns. These positive returns are often larger (in absolute value) than the negative returns observed for heavily shorted stocks. Thus, the positive information associated with low short interest, which is publicly available, is only slowly incorporated into prices, which raises a broader market efficiency issue. Our results also cast doubt on existing theories of the impact of short sale constraints.     

Do Publicly Traded Property–Casualty Insurers Cater to the Stock Market?

This article examines the catering theory in the insurance industry. We investigate whether managers of publicly traded insurers pursue a growth strategy catering to the stock market's preference. Two hypotheses are tested in this study: (1) an insurer will devote more efforts to increasing premium growth when the stock market places greater values on growth, and (2) this catering effect will be more pronounced at firms where managers have greater incentives to maximize short‐term stock prices. We find evidence supporting both hypotheses. Our study discovers a new channel through which the stock market and executive compensation affect insurance companies’ business strategies and the insurance market. The implication of the interplay between insurers and the stock market is significant and deserves future research.     

Asymmetric risk premium in value and growth stocks

There are two competing explanations for the existence of a value premium, a rational market risk explanation, whereby value stocks are inherently more risky than growth stocks, and a market over-reaction hypothesis, where agents overstate future returns on growth stock. Using asymmetric GARCH-M models this paper tests the predictions of the two hypotheses. Specifically, examining whether returns exhibit a positive (negative) risk premium resulting from a negative (positive) shock and the relative size of any premium. The results of the paper suggest that following a shock, volatility and expected future volatility are heightened, leading to a rise in required rates of return which depresses current prices. Further, these effects are heightened for value stock over growth stock and for negative shocks over positive shocks. Thus, in support of the rational risk interpretation, with a volatility feedback explanation for predictive volatility asymmetry.     

DotCom Mania: The Rise and Fall of Internet Stock Prices

This paper explores a model based on agents with heterogenous beliefs facing short sales restrictions, and its explanation for the rise, persistence, and eventual fall of Internet stock prices. First, we document substantial short sale restrictions for Internet stocks. Second, using data on Internet holdings and block trades, we show a link between heterogeneity and price effects for Internet stocks. Third, arguing that lockup expirations are a loosening of the short sale constraint, we document average, long‐run excess returns as low as ?33 percent for Internet stocks postlockup. We link the Internet bubble burst to the unprecedented level of lockup expirations and insider selling.     

Short sales,institutional investors and the cross-section of stock returns

Short-sale constraints are most likely to bind among stocks with low institutional ownership. Because of institutional constraints, most professional investors simply never sell short and hence cannot trade against overpricing of stocks they do not own. Furthermore, stock loan supply tends to be sparse and short selling more expensive when institutional ownership is low. Using institutional ownership as a proxy, I find that short-sale constraints help explain cross-sectional stock return anomalies. Specifically, holding size fixed, the under-performance of stocks with high market-to-book, analyst forecast dispersion, turnover, or volatility is most pronounced among stocks with low institutional ownership. Ownership by passive investors with large stock lending programs partly mitigates this under-performance, indicating some impact of stock loan supply. Prices of stocks with low institutional ownership also underreact to bad cash-flow news and overreact to good cash-flow news, consistent with the idea that short-sale constraints hold negative opinions off the market for these stocks.     

Short selling activity,price efficiency and fundamental value of IPO stocks

In this study, we take advantage of the unique features of the Taiwan stock market, where short selling is forbidden within the first six months following an IPO. We examine the effects of short selling on IPO price efficiency and the relation between short selling activities and the fundamental value of IPO stocks. We find that price efficiency is improved with increased short selling after the lifting of short sale constraints on IPO stocks. We also show that short sellers tend to target IPO stocks with low fundamental ratios, but simultaneously avoid stocks with high transaction costs. In addition, we provide empirical evidence that short sellers focus more on temporary price fluctuations rather than temporary fluctuations in fundamentals.     

Contrarian flows,consumption and expected stock returns

We investigate the relation between contrarian flows, consumption growth, and market risk premium. We construct a contrarian flows measure by summing up the capital flows to stocks that go against the total flow of the aggregate market. We show that the contrarian flows are negatively influenced by the same-quarter consumption growth. During bad times, the majority of investors who are affected by the negative shock reduce their equity exposure, and these extra supplies of risky assets are absorbed by contrarian investors who are least affected by the consumption shock. Using quarterly stock market data, we find that the contrarian flows forecast market returns at short-to-intermediate horizons. The predictability stems from the component that is explained by the consumption growth, and therefore the consumption growth contains valuable information about the market risk premium. Moreover, the predictability is stronger for growth stocks than for value stocks, and hence it negatively predicts the value premium. This is because the contrarian flows measure the market risk premium and growth stocks bear more discount rate risk than value stocks. Out-of-sample tests show that the main results are robust to data-snooping bias.     

Price clustering on the limit-order book: Evidence from the Stock Exchange of Hong Kong

We examine the clustering pattern in trade and quote prices on the electronic limit order book of the Stock Exchange of Hong Kong (SEHK). Earlier research into clustering focuses on transaction prices only. We study clustering on quote prices over a maximum of five queues on the limit order book. We observe an abnormally high frequency of even and integer prices in trade and quote prices for all tick size groups on the SEHK. The deeper quotes display stronger clustering than the best quotes, indicating that the farther away the quotes are from the best queue, the less information they carry. Our analysis further reveals that an extremely fine tick size itself works as a binding constraint to hinder the price resolution process. We also find that short sale prohibition imposed on the majority of stocks listed on the SEHK causes a significant bias in clustering towards the ask side of the limit order book. This implies that a short sale prohibition impairs efficient price discovery in the market.     

Failures to Deliver,Short Sale Constraints,and Stock Overvaluation

Studying a large sample of publicly available data on failures to deliver, we find that stocks reaching threshold levels of failures become significantly overvalued. Where short sale constraints are especially binding, we report extreme overpricing and subsequent reversals. These findings support the overvaluation hypothesis, although the mispricing is likely to be difficult to arbitrage because of extreme shorting costs. In addition, threshold stocks with low short interest become more overvalued than threshold stocks with high short interest. This suggests that the level of short interest reflects supply‐side effects when the examination conditions on the difficulty of borrowing shares.     

Security price formation and informed trading with constrained short selling

Short sale orders account for a substantial portion of trading volume in recent years. This paper develops a sequential trade model with constrained short selling to derive the effect on prices when the market maker can observe short selling in the order flow. The model predicts that market quotes will adjust differently to short sales and regular sales. Furthermore, the model shows that the probability of informed trading is impacted both by the level of short sale constraints and the intensity of actual short sale trades. Simulation evidence confirms that estimates of the probability of informed trade are improved when accounting for past short selling activity. The results demonstrate the information benefits of short selling transparency.

     

Short Sale Constraints and Dispersion of Opinion: Evidence from the Indian Equity Market

Short sale constraints can inflate market prices, as bearish investors cannot act on their market views. The paper uses data from the Indian equity market to test whether opinion dispersion leads to higher overpricing when short sales are prohibited. The Indian equity market provides a natural testing environment, as short sales were banned between 2001 and 2008. The empirical results offer supportive evidence of the relation between opinion dispersion and overpricing in a market with short sale constraints.