China has a new most valuable listed company, and it makes the chips inside your phone. CXMT, formerly ChangXin Memory Technologies, closed its Shanghai debut up 466% on Monday, the South China Morning Post reported. That values the Hefei firm at 3.28 trillion yuan, or about $485bn.

The numbers are hard to overstate. CXMT priced its IPO at 8.66 yuan a share, opened at 49.50 and touched 55.03 during the session. It raised 57.92 billion yuan, about $8.6bn, rising to $9.8bn if the overallotment is exercised. That is Asia’s biggest listing this year, and the second largest in Chinese history behind Agricultural Bank of China in 2010.

Turnover topped 140 billion yuan. No mainland-listed stock had ever crossed 100 billion in a single day. CXMT alone accounted for nearly 7% of all trading on China’s onshore market, Bloomberg reported.

It now outranks Industrial and Commercial Bank of China, worth 2.6 trillion yuan. A ten-year-old memory maker is worth more than the country’s biggest bank. Only Hong Kong-traded Tencent is larger.

Why memory, why now