At the close on June 25, 2021, the Russell indices will be rebalanced. This involves the Russell 1000, the Russell 2000, the Russell microcap index, and several others. Thousands of stocks are impacted by what Russell calls its 'reconstitution.' Typically the day on which the reconstitution is down is one of the highest volume days of the year as a slew of huge blocks are transferred to various index funds.
The preliminary list of the stocks that will be added and deleted to the Russell indices was released at the close on Friday, June 4, 2021. The list will be updated on June 11 and June 18 before becoming final on June 25.