NEW YORK: FTSE Russell reconfigured its indexes at the close in an annual event that triggered the highest trading volume for any session in almost five years and added to Friday’s high volatility in the US stock market.

Trades in about 933 million shares representing $20.6 billion were executed in Nasdaq’s “closing cross” in 0.8 seconds across some 2,464 Nasdaq-listed stocks, according to bourse.

The closing cross brings together the buy and sell interest in specific Nasdaq, NYSE and NYSE MKT stocks and executes all shares for each stock at a single price, Nasdaq said. The closing prices determined by the closing cross are widely used throughout the industry.

Volume on US exchanges Friday totaled 15.3 billion, the highest since August 2011, according to Bats Global Markets, with Britain’s vote to leave the European Union also rattling investors.

On the Russell reconstitution day in June 2015, US equity volume was just 10.1 billion, Bats data showed.

Newly reconstituted index membership will take effect when markets open on Monday.

A final list of the changes also is due to be released on Monday, but Wall Street analysts said preliminary lists of the changes showed that in the Russell 2000 small company index, financial firms and consumer staples companies lose weighting and materials companies and producer durables have a stronger role.—Reuters