Mainland stocks soared more than 10 percent at the open on Tuesday as traders resumed a blistering rally after a week-long break hoping for more economy-boosting measures from Beijing, which unveiled a slew of stimulus last month.

The Shanghai Composite Index surged 10.13 percent, or 337 points, to 3,674, to its highest point since mid-2022 while the Shenzhen Composite Index piled on 11.37 percent, or 219 points, to 2,146, its best level since December 2021.

Before the break, China announced the most aggressive stimulus measures since the pandemic and the CSI300 gained 25 percent over five sessions. Turnover soared as heavy buying strained brokers and trading systems, and last Monday the CSI300 and the Shanghai Composite both notched their largest gains since 2008.

Authorities have cut rates and hinted at fiscal support to shore up an economy that, by Chinese standards, is ailing.

Before the Golden Week holiday break, hedge fund manager David Tepper said on CNBC the moves were encouraging enough that he would buy "everything" on China.

But gains have been so large that others now urge caution.

"China's weighting in the MSCI EM Index rose from 24 percent in August to 30 percent now, and its continued out-performance may drive a self-reinforcing 'pain-trade' before the year-end," Bank of America analysts said in a note on Monday.

However, they said, the "'buy everything' stage will be over soon," with market momentum, fiscal support, earnings, the US election and further policy settings all part of the outlook.

"Consumer, property (and) broker stocks could be profit-taking candidates ... big cap internet and high-yield SOEs are our preferred exposure," they said. (Agencies)