Stocks in China posted their biggest intraday swings since 2010 on Friday as transactions on the mainland's exchanges exceeded 1 trillion yuan ($163 billion) and the benchmark index traded near four-year highs.

The Shanghai Composite Index ended 1.5 percent higher at 2,942.23 points after rising as much as 2.7 percent and falling 3 percent during the day.

"The market is becoming very speculative," said Wang Zheng, the Shanghai-based chief investment officer at Jingxi Investment, which oversees about $120 million. "Such a rally is unsustainable for sure. The market will be in for a very wild ride up and down next week."

The Shanghai index's 165-point swing during the first 90 minutes of trading was the biggest since November 2010.

The SCI's 19 percent rally over the past month, the most among 93 global indexes tracked by Bloomberg, is spurring mainland investors to open share accounts at the fastest pace in three years and sending trading values to all-time highs.

Trading values were poised to hit a fresh record. Shares worth 431.5 billion yuan had changed hands on the exchange as of the mid-day break. That made up 82 percent of the full-day record turnover of 529.4 billion yuan set on Wednesday.

The CSI 300 Index rose for an 11th day, adding 0.7 percent. Hong Kong's Hang Seng China Enterprises Index advanced 1.7 percent, while the Hang Seng Index climbed 1.1 percent.

The Bloomberg China-US Equity Index, the measure of the most actively traded Chinese companies listed in the United States, added 2.5 percent on Thursday.

The Shanghai Composite has advanced 39 percent this year, heading for the biggest annual gain since 2009. It is valued at 10.7 times 12-month projected earnings, the highest level since August 2011, according to data compiled by Bloomberg.

"China's stock rally in the last two weeks can't be explained by any economic fundamentals," said Ken Peng, a strategist at Citigroup Inc's private bank in Hong Kong. "If the central bank shifted course in easing, stock market rally would fizzle away very quickly."

The SCI rallied 9.4 percent this week with banks and brokers surging on speculation increased trading will boost profits and the People's Bank of China will cut reserve requirement ratios.

The central bank cut interest rates for the first time in two years last month to support economic growth. Recent data show manufacturing growth trailed estimates and export growth slowed.

Trade data for November are scheduled for release on Dec 8.