SHANGHAI: China shares ended lower on Wednesday after a volatile session as US actions against Hong Kong dented the market sentiment, but the bull-run-triggered heavy trading kept its momentum.

At the close, the Shanghai Composite index was down 1.56% at 3,361.30, extending losses from the mid-day session.

The blue-chip CSI300 index was down 1.29%, with its financial sector sub-index lower by 2.26%, the consumer staples sector up 0.93%, the real estate index down 2.88% and the healthcare sub-index up 1.78%. The smaller Shenzhen index ended down 2.07% and the start-up board ChiNext Composite index was weaker by 1.596%. "Key catalysts for the A-share bull run are still intact but we caution against near-term regulatory cool-down measures and resurgence of US-China tensions," Laura Wang, equity strategist with Morgan Stanley wrote in a note.

So far this year, the Shanghai stock index is up 10.2% and the CSI300 has risen 15.8%, while China's H-share index listed in Hong Kong is down 7.1%. Shanghai stocks have risen 12.62% this month with huge volume of hands exchanged. US president Donald Trump on Tuesday ordered an end to Hong Kong's special status under US law to punish China for what he called "oppressive actions" against the former British colony, and signed a bill approved by the US Congress to penalize banks doing business with Chinese officials who implement the new security law.