U.S. stock indexes plunged almost 4 percent on Monday as investors, rattled about China¡¯s economy, sold heavily in an unusually volatile session that confirmed the benchmark S&P 500 was formally in a correction.

The Dow Jones industrial average briefly slumped more than 1,000 points ¡ª its most dramatic intraday trading range ever ¡ª with key component Apple falling heavily only to claw back but end down 2.5 percent.

It was the S&P 500¡¯s worst day since 2011 and followed an 8.5 percent slump in China markets, which sparked a sell-off in global stocks along with oil and other commodities.