NYSE Arca, the New York Stock Exchange’s sister market, widened the amount prices are allowed to move during the opening minutes of trading.

Under the new system, securities valued at 1 cent to $25 can rise or fall 10 percent from the prior day’s level. Those between $25.01 and $50 can move 5 percent, while stocks above $50 can move 3 percent. Previously, the limits were 5 percent, 2 percent and 1 percent, respectively.

The system, which only affects market orders placed in the auction that starts each day’s trading session, takes effect Sept. 8.

One of NYSE Arca’s primary businesses is serving as the home market for hundreds of exchange-traded funds. Many of those had unusual price swings when the market opened on Aug. 24, prompting trading halts that reverberated throughout the industry. Stocks ended up having one of their most volatile sessions in years.

NYSE Arca and the New York Stock Exchange are both owned by Intercontinental Exchange Inc.

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