The Nasdaq market came under intense pressure from regulators and class-action lawsuits following allegations of tacit collusion by Christie and Schultz (1994). This article examines the changes in transaction costs on the Nasdaq from January 1993 through June 1996 using 16 million trades in 30 stocks. Effective spreads cannot be estimated during 1995 and 1996 because time-stamps of trades and quotes cannot be matched. However, the autocovariance spread estimator of Roll (1984) works well with intraday data over this period. This spread estimator reveals that trading costs declined significantly for 29 of the 30 stocks over 1993-1996.

This paper examines the timing of, and reaction to, calls of callable warrants. Three main findings emerge. First, unlike convertible bonds or preferred stock, callable warrants are called almost as soon as possible. Second, there is a negative price reaction of about 3 percent when a call is announced. Finally, at the completion of a call, the stock price rebounds by an average of 7 percent. The total reaction from announcement through completion of the call is a positive excess return of about 4 percent.

This paper uses a sample of over 25,000 daily warrant prices to empirically investigate potential problems with the commonly used warrant pricing model proposed by F. Black and M. Scholes as an extension of their call option model. One problem seems to be especially important: the constant variance assumption of the dilution adjusted Black-Scholes model appears to cause biases in model prices for almost all warrants and over the entire sample period. The authors show that more accurate price forecasts are obtained with a specific form of the constant elasticity of variance model.

Stocks that are expensive to borrow underperform significantly and for long periods of time. Every share must be held by an investor who does not lend it out and, hence, loses money. I find no evidence that investors hold these stocks in anticipation of lending them in the future. Instead, investors appear to hold these stocks for short-term trading. When turnover is high, high-fee stocks are overpriced and underperform. When turnover is low, high-fee stock prices are low, and they earn positive returns. More Robinhood investors hold shares when turnover is high than when it is low.

A short squeeze occurs if borrowed shares are recalled and the short seller is unable to find another source of shares. This forces the short seller to terminate a position early. For most stocks, the probability of a short squeeze is very low. Short squeezes, however, are not unusual for the hardest to borrow stocks. For these stocks, trading costs from squeezes are high and have a significant impact on the returns to short selling. For hard-to-borrow stocks, short sellers also miss out on significant abnormal returns because squeezes force them to close positions.