Hong Kong (CNN Business) China's beaten-down stock market had its best day in more than two and and a half years on Monday.

The benchmark Shanghai Composite index surged more than 4% after a rare concerted intervention by senior officials to talk up the country's struggling economy and markets.

China is one of the world's worst performing stock markets this year. The Shanghai index is down more than 25% since late January, hurt by fears about the economy and the impact of the trade war with the United States.

But investors have been re-energized by a recent attempt by top Chinese economic and financial officials to ease investors' concerns.

"It's rare to see officials make this kind of public comment on the stock market," said Dickie Wong, head of research at Hong Kong-based stock broker Kingston Financial. "It's definitely boosting market sentiment."

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