Shanghai equity investors enjoyed the country's best average returns from the A-share market during the first four months－156,400 yuan ($25,200), compared to a national average of 14,000 yuan, according to data released on Monday by Hithink RoyalFlush Information Network Co Ltd.

The figures showed average Beijing investors were second in the rankings with 80,200 yuan, followed by those in Zhejiang province at 36,900 yuan, said the Hangzhou-based online financial information provider.

The Shanghai Composite Index closed at 4,441.66 points on April 30, up 37.3 percent compared with Dec 31. Of the A-share market's 2,547 stocks, 99.5 percent had risen by the end of the month.

"The strong investment returns by Chinese equity investors, especially Shanghai investors at 156,000 yuan, showed the A-share market is booming, but risks are now brewing," said Li Daxiao, chief economist at Yingda Securities Co Ltd.

According to Li's calculations, 1 yuan is now worth 0.19 yuan of net assets on the main board, and 0.09 yuan of net assets on the ChiNext board, China's Nasdaq-style market.

"A-share market valuations will drop as China implements its new registration-based IPO system and some senior managers at listed companies sell shares," said Li.

One fund manager at a Chinese asset management company, who declined to be named, said good investment returns in the future will not be unusual, and "as China's economic transition has not yet ended and liquidity remains good, "so I feel optimistic about the A-share market".

He cautioned, however, that average investment returns do not mean that everyone wins, because around 10 percent of investors actually make 90 percent of the money.

The April investor confidence index of the Chinese securities market was 65.2, increasing 26.6 percentage points year-on-year, according to a report by the China Securities Investor Protection Funds, and investor confidence has now been positive for 11 months.

Li said Chinese equity investors should be reminded that it remains difficult to keep their money and that it is dangerous to borrow money to make equity investments, adding that while some blue-chip stocks still offer opportunities, many stocks remain high risk.