Law Commons^™

Externalities And The Common Owner, Madison Condon

Faculty Scholarship

Due to the embrace of modern portfolio theory, most of the stock market is controlled by institutional investors holding broadly diversified economy-mirroring portfolios. Recent scholarship has revealed the anti-competitive incentives that arise when a firm’s largest shareholders own similarly sized stakes in the firm’s industry competitors. This Article expands the consideration of the effects of common ownership from the industry level to the market-portfolio level, and argues that diversified investors should rationally be motivated to internalize intra-portfolio negative externalities. This portfolio perspective can explain the increasing climate change related activism of institutional investors, who have applied coordinated shareholder power to …