Markets Magazine

Index Providers Rule the World—For Now, at Least

Decisions about what to include are leaving some on the outs.

In September 2015, Peru’s then-finance minister abruptly changed his plans and hopped on a jet to New York. By the time ­Alonso Segura Vasi landed in the U.S., officials from the country’s central bank and ­securities regulator were also en route to join him.

What prompted a bevy of Peruvian officials to make the eight-hour journey wasn’t a matter of urgent statecraft or diplomacy. Instead, it was a rumor that the financial company MSCI Inc. might oust the South American country from its widely followed emerging-markets index, a prospect that Vasi knew required ­immediate intervention.