Stocks opened with sharp losses Friday morning for the fourth straight day with the Dow falling almost 300 points. The markets are responding to uncertainty in China and a lack of positive economic news.

"I think uncertainty about China (and) general negativity is weighing on the market. There's a lack of positive economic news to motivate buyers," David Kelly, chief global strategist at JPMorgan Funds said, according to CNBC. He added, "there's nothing particularly negative in the U.S. economic outlook." 

The Dow Jones industrial average fell more than 290 points in morning trading and the Nasdaq Composite lost more than 1.5 percent, USA Today reports. Thursday, the Dow fell 358 points, its largest decline since Nov. 9, 2011.

All 10 sectors of the S&P 500 were down Friday, with the consumer discretionary and technology sectors being the biggest losers.

Oil also continues to fall, with U.S. crude falling 75 cents to $40.30 a barrel and Brent crude falling 60 cents to $46.02 in London.

Asian markets responded to the U.S. stock market's big drop Thursday by falling on Friday. Weak Chinese manufacturing data and other factors are worrying investor's about the country's economy.

The Shanghai composite index in China fell by over 4 percent Friday. Marketwatch reports China's benchmark index is down 32 percent since June 12.

China's Caixin purchasing managers' index fell to a low score of 47.1, down from July's 47.8 points. The index is based on a scale of 100 with anything below 50 showing a contraction.

China's economy has caused the Shanghai to fall this week, even with the massive government intervention. Last week, Beijing devalued the Chinese yuan, causing other emerging countries to panic that they will face tougher competition from lower-priced Chinese exports.

Japan's finance minister, Taro Aso, told the Nikkei newspaper that China was a big reason why stocks fell in Tokyo, according to USA Today.

"There's a lot of systemic fear with growth slowing in China ... but nobody really knows what the actual data is," John Caruso, senior market strategist at RJO Futures, told CNBC. "With China taking the drastic measure of actually devaluing their currency (last week) many people are believing things are much worse than they're leading us on to believe."