Stock market measures in the U.S. fell Tuesday after strong gains in the first hours of trading.

The Dow Jones Industrial Average index closed Tuesday with a loss of more than one percent, after rising earlier in the day by almost 3 percent.

The volatility in stock prices came after China’s stock exchanges dropped sharply for the second day. In Shanghai, the stock index fell almost 8 percent, after Monday’s drop of 8.5 percent.

Investors blame concerns over an economic slowdown in China and its effects on growth around the world.