NEW YORK - As the global equity markets collapsed Monday amid economic growth concerns, analysts believe the world's stock markets could be more volatile in the future.

The Chinese stock markets had their worst day in eight years Monday with the benchmark Shanghai Composite Index tumbling 8.49 percent to close at 3,209 points.

The Dow tumbled 588 points, or 3.58 percent, to 15,871, after sliding more than 1,000 points, or 6 percent at the opening. The S &P 500 shed 77.68 points, or 3.94 percent, to 1,893. The Nasdaq Composite Index sank 179.79 points, or 3.82 percent, to 4,526.

Investors are very fearful, said Thomas Lee, managing partner of research company Fundstrat. They are processing a lot of information - China's economic data, timing of the Federal Reserve' s rate rise, weak oil prices. It's too much worries for investors to keep holding the stocks.

Brendan Ahern, the portfolio manager of KraneShares, said that the US equity markets have done exceedingly well without a significant correction which has been overdue. And US valuations have risen along with stock prices unabated for seven years.

Stephen Roach, professor at Yale University and former chairman of Morgan Stanley Asia, said the US stock market has been supported by the Federal Reserve's expected move, not by the weak economic recovery.

"That's all we've been concerned about. The support from the Fed was artificial, but the policies are not necessary for the fundamental change of the economy," he said.

Now signals indicated that the US central bank wanted to start increasing interest rate to stop the quantitative easing. A lot of stimulants to the stock market have been made by the Federal Reserve is now in the process of being withdrawn.

Investors also saw the positive side of the market. Thomas Lee viewed it as a correction or pullback of the market. The US equity market is still supported by the strong housing market and low gasoline prices which could help consumption.

Markets are concerned about China's economy, said Lee, but was quick to add that the economic situation in China is probably better than what investors believed. The stock market fell back so quickly, the possibility of recovering quickly is likely as well, he noted.

Brendan Ahern suggested that investors should recognize that there are great valuations and growth opportunities outside of the US, such as Chinese equities listed in both the onshore and offshore markets.

"Buying China's onshore blue chip companies and US listed e-commerce companies today is never easy though buying at today's valuations is usually rewarded in the long run," Ahern said.