China's benchmark Shanghai Composite Index tumbled to the lowest level in 13 months on Tuesday, with some people assuming that the country's financial system is under attack by overseas investors. The index fell 6.42 percent from the previous trading day, and other Asian stock markets also slumped.

The deep fall came after China's State media had warned overseas investors against speculative attacks on the Chinese economy.

The Xinhua News Agency said that some people believe the Chinese capital market is experiencing a major crisis and some of them are trying to take advantage.

Billionaire investor George Soros recently warned of a possible financial crisis in Asia and said he was betting against Asian currencies.

This led to further speculation amid Tuesday's sell-off that overseas investors are seeking to make gains by deliberately shorting mainland-listed shares.

Short selling is selling a stock that isn't owned by the seller, in the anticipation that the price will go down so that a profit can be made when the stock is repurchased. It can have the effect of exacerbating downward pressure and volatility in the market.

However, despite claims by some people that overseas investors are shorting mainland stocks, it should be noted that this is not the main reason for the slump on Tuesday.

Investors should calmly analyze the complicated reasons behind Tuesday's sell-off.

The central bank surprised the market Tuesday morning by once again pumping liquidity into the interbank market through its open market operations.

The move further reduced the likelihood of an imminent cut in banks' reserve requirement ratio (RRR).

This added to market pessimism that had been exacerbated by the recent fall in crude oil prices, and pushed down A-shares further.

But it doesn't mean the country now has less ability to maintain stability in the stock market or that shares will continue to decline. The central bank may yet resort to more drastic measures like an RRR cut to help stabilize the market if the situation continues to deteriorate.

Besides, manipulating the stock market is illegal under Chinese law and malicious short-selling behavior will face legal consequences.

Measures were launched by the Ministry of Public Security and the China Securities Regulatory Commission after the stock market tumble last summer, including a probe into malicious short selling of stocks. So far, several financial institutions and some investors have been investigated.

Cracking down on illegal market activities will play an important role in stabilizing the market and restoring investor confidence.

At the same time, normal investment behavior by overseas investors should be encouraged.

The author is a reporter with the Global Times. bizopinion@globaltimes.com.cn