The addition of Tesla into the S&P 500 at the close this Friday will be one of the biggest trading days in history, but it is only the most recent example of an ongoing trend: index managers who make the decisions of what goes in and out of these indexes are becoming increasingly influential.
“Rebalancings have become major trading events because more investors are tied to indexes, so the volume of trading during rebalances has gone way up,” Harry Whitton from market maker Old Mission told me.
