(Yicai Global) Feb. 27 -- Stock markets on the Chinese mainland had a rocky afternoon of trading today as more than two weeks of solid gains showed sure signs of slowing down.

The large-cap dominated Shanghai Composite Index managed to finish up 0.42 percent at 2,953.82 after peaking at 2,997.49 -- 2 percent higher than opening to mark an eight-month high. But the Shenzhen Component Index slid 0.92 percent to 9,005.77 and the ChiNext Price Index, which tracks growth enterprises in Shenzhen, slumped 1.72 percent to 1,520.42.

Trading volume came in at CNY891.2 billion (USD133.4 billion) after two straight days of multi-year highs above CNY1 trillion, as investors were torn between betting on further gains or cashing out on the market's recent success.

China's mainland markets have been soaring since trading resumed on Feb. 11 after the week-long Chinese New Year holiday, with the three major indexes setting multi-month highs earlier this week. The cumulative rise of each of the indexes was between 14.4 percent and 28.3 percent at yesterday's intraday peaks.

More than half of all sectors closed lower today, with the previously red hot smallcap market struggling the most. Only a handful of sectors came out on top, led by telecom service providers. China Unicom came out swinging after state-backed CCTV reported during the lunch break that it had achieved full 5G coverage at Tiananmen Square, a massive tourism and political hub in Beijing.