Chinese chipmaker shares surge nearly 470% in blockbuster stock market debutReutersShares in China's biggest memory chip maker have soared by nearly 470% as they made their debut on the Shanghai Stock Exchange's tech-heavy Star Market.The surge has pushed ChangXin Memory Technologies' (CXMT) stock market valuation to around 3.3 trillion yuan ($487bn; £365bn), making it the most valuable listed company in mainland China.The spectacular debut comes despite a sharp sell-off in technology stocks aro...