China’s largest semiconductor IPO on record instantly produced the mainland market’s most valuable listed company, highlighting investors’ enthusiasm for Beijing’s AI ambitions.

Shares of CXMT Corp., China’s largest maker of DRAM memory chips, surged as much as 535% in their debut in Shanghai on Monday. The stock closed 466% higher.

The company previously known as ChangXin Memory Technologies raised 57.92 billion Chinese yuan, or about $8.6 billion, with proceeds potentially rising to 66.6 billion yuan if an overallotment option is fully exercised. It was China’s second-largest mainland IPO on record, behind Agricultural Bank of China’s 2010 offering.

At the opening price of 49.50 yuan — compared…