We adopt a power law framework to measure the concentration of daily trading among the different stocks on the US market. Our analysis of the trends of daily concentration over the last five decades reveals that trading concentration is lower on Mondays and the day after a long weekend. These...

Firms added to (deleted from) the S&P 600 index experience a significant price increase (decrease) at announcement. Firms that newly enter (exit) the S&P universe experience a larger price increase (decrease) than firms that move between S&P indexes. Trading volumes are higher after the...

We examine the effects of stock repurchase announcements on the value of the announcing insurance firms and on the value of rival insurance firms. We find that insurance firms experience a significant increase in value at the time of the announcement. Repurchasing firms continue to earn excess...

This study analyzes bid-ask spreads surrounding announcements of open-market share repurchase programs for a sample of 248 announcements of repurchase programs by NYSE firms over the period January 1984 through June 1988. The sample includes 158 announcements of new programs and 90 announcements...