In finance, there exists the question of whether the demand for common stock is perfectly elastic. That is, are there perfect substitutes for a firm’s common shares? If so, then the demand curve for its shares should be perfectly horizontal. If not, then one would expect a negatively sloped demand for shares. If demand is horizontal, then an increase in demand (owing to some influence other than positive new information regarding the firm’s outlook) would not increase the share price. In contrast, a purely “mechanical” increase in demand would be expected to increase the price if the demand were negatively sloped. One study looked at evidence from 31 stocks whose weights on the Toronto Stock Exchange 300 Index were changed, owing purely to fully anticipated technical reasons that apparently had no relationship to new information about those firms.12 That is, the demand for those shares shifted rightward. The authors found that there was a statistically significant 2.3 percent excess return associated with those shares, a finding consistent with a negatively sloped demand curve for common stock.