Why you delete them, of course even if the two names in question happen to be Europe's two largest banks, Deutsche Bank and Credit Suisse.

Moments ago, STOXX Ltd, the operator of Deutsche Boerse Group's index business, announced component changes in the STOXX Europe 50 Index due to the fast-exit rule. All changes become effective with the open of markets on Aug. 8, 2016.

What is the Fast Exit rule? "The rule states that a component is deleted from the Dow Jones EURO STOXX 50 or Dow Jones STOXX 50 indexes if it ranks 75 or below on the respective index's monthly selection lists for a consecutive period of two months. Deleted components for all three indexes will be replaced by the highest ranking non-components on the monthly selection list. Component changes will be announced on the first trading day of the month following the publication of the monthly selection lists, implemented on the close of the fifth trading day and effective the next trading day."