<p>In Chapter 1, I document a negative (positive) relationship between changes in large (small) blockholders' ownership and abnormal returns. The evidence in this paper suggests that an increase in the relatively large blockholders' ownership raises the consumption of private benefits while an increase in the relatively small blockholders' ownership constrains large blockholders from expropriating minority shareholders. Moreover, I find an inversely U-shaped relationship between changes in the largest blockholders' ownership and firm value. As large blockholders' ownership and control increase, the negative effect of firm value driven by expropriating minority shareholders starts to exceed the incentive benefits of monitoring by the largest blockholder. I also show that the negative relationship between changes in institutional investors' control and abnormal returns declines as analysts' following increases.</p><p>In Chapter 2, I study the role of trading as a governance mechanism. I hypothesize that governance through trading plays a significant monitoring role in practice and that engaging in "voice" and "exit" can be substitutes. I show that abnormal turnover following earnings announcements is significantly higher for firms with large institutional blockholders than for those with small individual</p><p>shareholders. For firms with majority institutional ownership, I demonstrate that abnormal trading is higher for firms with multiple blockholders than for those with a single large blockholder and that abnormal trading increases with the number of institutional investors and declines with the percent of stocks owned by the</p><p>largest institutional investor. Moreover, this excess trading is driven by mutual fund investors, which are non-interventionist and thus are more likely to engage in "exit" than "voice". I also show that for firms with large institutional blockholders, abnormal trading following public announcements increases with liquidity.</p> / Dissertation