We investigate the relation between common institutional ownership of the firms in an industry and product market competition. We find that common ownership is neither robustly positively related with industry profitability or output prices nor is it robustly negatively related with measures of nonprice competition, as would be expected if common ownership reduces competition. This conclusion holds regardless of industry classification choice, common ownership measure, profitability measure, nonprice competition proxy, or model specification. Our point estimates are close to zero with tight bounds, rejecting even modestly sized economic effects. We conclude that antitrust restrictions seeking to limit intra-industry common ownership are not currently warranted.

We examine the impact of investor coordination on governance. We identify coordinating groups of investors (cliques) as those connected through the network of institutional holdings. Clique members vote together on proxy items: a one standard deviation increase in clique ownership more than doubles votes against low quality management proposals. We use the 2003 mutual fund trading scandal to show that this effect is causal. These findings suggest coordination strengthens governance via voice. Coordination, however, also weakens governance via threat of exit. Clique owners exit positions more slowly, and firm value responds negatively to liquidity shocks when clique ownership is high.