General view of tourists taking selfies at North Bund in Shanghai, China, as Typhoon Dolphin approaches the country.

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China's benchmark CSI 300 index on Thursday entered bear-market territory, falling 20% from its June peak, as a prolonged sell-off in its equities deepens.

The index, which tracks 300 of the largest stocks listed in Shanghai and Shenzhen, has declined for 10 consecutive weeks and is down 2.6% so far this week, underscoring sustained pressure on Chinese equities, data from LSEG showed. The index was more than 1% lower Thursday.

Jordan Cvetanovski, chairman and CIO at Pella Funds, said China's equity market continues to face structural challenges, particularly as the world's second-largest economy grapples with the fallout from years of excess capacity and overinvestment.

"I think China is really struggling with reining in the problems that they've had in the past from the overbuild of capacity and other things," Cvetanovski told CNBC, pointing to…