Various theories have been proposed to explain momentum in stock returns. We test the gradual-information-diffusion model of Hong and Stein (1999) and establish three key results. First, once one moves past the very smallest stocks, the profitability of momentum strategies declines sharply with firm size. Second, holding size fixed, momentum strategies work better among stocks with low analyst coverage. Finally, the effect of analyst coverage is greater for stocks that are past losers than for past winners. These findings are consistent with the hypothesis that firm-specific information, especially negative information, diffuses only gradually across the investing public. SEVERAL RECENT PAPERS HAVE DOCUMENTED that, at medium-term horizons ranging from three to 12 months, stock returns exhibit momentum-that is, past winners continue to perform well, and past losers continue to perform poorly. For example, Jegadeesh and Titman (1993), using a U.S. sample of NYSE/ AMEX stocks over the period from 1965 to 1989, find that a strategy that buys past six-month winners (stocks in the top performance decile) and shorts past six-month losers (stocks in the bottom performance decile) earns approximately one percent per month over the subsequent six months. Not only is this an economically interesting magnitude, but the result also appears to be robust: Rouwenhorst (1998) obtains very similar numbers in a

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Recent equity carve-outs in US technology stocks appear to violate a basic premise of financial theory: identical assets have identical prices. In our 1998-2000 sample, holders of a share of company A are expected to receive x shares of company B, but PA < xPB . A prominent example involves 3Com and Palm. Arbitrage does not eliminate these blatant mispricing due to short sale constraints, so that B is overpriced but expensive or impossible to sell short. Evidence from options prices shows that shorting costs are extremely high, eliminating exploitable arbitrage opportunities. Can the market add and subtract? - Page 1 There are two important implications of the efficient market hypothesis. The first is that it is not easy to earn excess returns. The second is that prices are correct in the sense that prices reflect fundamental value. This latter implication is, in many ways, more important than the first. Do asset markets offer rational signals to the economy about wher...

Motivated by the behavior of asset prices, trading volume and price volatility during historical episodes of asset price bubbles, we present a continuous time equilibrium model where overconfidence generates disagreements among agents regarding asset fundamentals. With short-sale constraints, an asset owner has an option to sell the asset to other overconfident agents when they have more optimistic beliefs. As in Harrison and Kreps (1978), this re-sale option has a recursive structure, that is, a buyer of the asset gets the option to resell it. Agents pay prices that exceed their own valuation of future dividends because they believe that in the future they will find a buyer willing to pay even more. This causes a significant bubble component in asset prices even when small differences of beliefs are sufficient to generate a trade. In equilibrium, large bubbles are accompanied by large trading volume and high price volatility. Our model has an explicit solution, which allows for several comparative statics exercises. Our analysis shows that while Tobin’s tax can substantially reduce speculative trading when transaction costs are small, it has only a limited impact on the size of the bubble or on price volatility. We also give an example where the price of a subsidiary is larger than its parent firm. This paper was previously circulated under the title “Overconfidence, Short-Sale Constraints and Bubbles.”

An Analysis of the Equity Lending Market With a year of equity loans by a major lender, we measure the effect of actual shortselling costs and constraints on trading strategies that involve short-selling. We find that wholesale costs of equity loans for shorting IPO’s, DotComs, large-cap, growth and lowmomentum stocks are small relative to the documented benefit, and that investors who can short only stocks that are cheap and easy to borrow can closely track the returns of unconstrained investors. Most IPO’s are loaned on their first settlement days and throughout their first months, and the underperformance around lockup expiration is significant even for the subset of stocks that are cheap and easy to borrow. The effect of short-selling frictions appears strongest with merger arbitrage. Acquirers ’ stock is expensive to borrow, especially acquirers with small market capitalizations. The additional cost paid in merger arbitrage positions does not significantly affect profits, but the shortage of available issues reduces profits by more than half. 2 The finance literature identifies a number of situations where one asset appears overvalued relative to another, in the sense that an investor apparently profits from

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Abstract: We develop a model of stock prices in which there are both differences of opinion among investors as well as short-sales constraints. The key insight that emerges is that breadth of ownership is a valuation indicator. When breadth is low i.e., when few investors have long positions in the stock this signals that the short-sales constraint is binding tightly, implying that prices are high relative to fundamentals and that expected returns are therefore low. Thus reductions in breadth should forecast lower returns, while increases in breadth should forecast higher returns. Using quarterly data on mutual fund holdings over the period 1979-1998, we find evidence supportive of this prediction: stocks whose change in breadth in the prior quarter places them in the lowest decile of the sample underperform those in the top change-in-breadth decile by 6.38 % in the first twelve months after portfolio formation. After adjusting for size, book-tomarket and momentum, the corresponding figure is 4.95%.

Stocks can be overpriced when short-sale constraints bind. We study the costs of short-selling equities from 1926 to 1933, using the publicly observable market for borrowing stock. Some stocks are sometimes expensive to short, and it appears that stocks enter the borrowing market when shorting demand is high. We find that stocks that are expensive to short or which enter the borrowing market have high valuations and low subsequent returns, consistent with the overpricing hypothesis. Size-adjusted returns are 1 % to 2 % lower per month for new entrants, and despite high costs it is profitable to short them.

We build a model that helps explain why increases in liquidity⎯such as lower bid-ask spreads, a lower price impact of trade, or higher turnover⎯predict lower subsequent returns in both firm-level and aggregate data. The model features a class of irrational investors, who underreact to the information contained in order flow, thereby boosting liquidity. In the presence of short-sales constraints, high liquidity is a symptom of the fact that the market is dominated by these irrational investors, and hence is overvalued. This theory can also explain how managers might successfully time the market for seasoned equity offerings, by simply following a rule of thumb that involves issuing when the SEO market is particularly liquid. Empirically, we find that: i) aggregate measures of equity issuance and share turnover are highly correlated; yet ii) in a multiple regression, both have incremental predictive power for future equal-weighted market returns.

Stocks can be overpriced when short sale constraints bind. We study the costs of short selling equities, 1926-1933, using the publicly observable market for borrowing stock. Some stocks are sometimes expensive to short, and it appears that stocks enter the borrowing market when shorting demand is high. We find that stocks that are expensive to short or which enter the borrowing market have high valuations and low subsequent returns, consistent with the overpricing hypothesis. Size-adjusted returns are one to two percent lower per month for new entrants, and despite high costs it is profitable to short them.