The Securities and Exchange Commission adopted new rules Friday to expand the trading halts it implemented after the May 6 “flash crash” and to harmonize stock exchanges’ procedures for breaking erroneous trades.
A pilot program to limit price swings in stocks will be expanded from just the stocks in the S&P 500 stock index to all stocks in the Russell 1000 index and to certain exchange-traded funds.

Under the program, a five-minute pause in trading is triggered whenever a stock experiences at least a 10 percent price swing within five minutes.