The article argues that index managers have incentives to be excessively deferential to portfolio-company managers and documents substantial concentrated voting power. The 25% figure concerns votes cast, not beneficial ownership.
In a recent empirical study, The Specter of the Giant Three, we document that the Big Three collectively vote about 25% of the shares in all S&P 500 companies.
The article argues that index managers have incentives to be excessively deferential to portfolio-company managers and documents substantial concentrated voting power. The 25% figure concerns votes cast, not beneficial ownership.