Pop! Few events in financial markets this year were as hotly anticipated as the listing on September 14th of Arm, a British chipmaker whose designs are found in nearly every smartphone. The debut, on New York’s Nasdaq stock exchange, was a resounding success. The share price climbed by 25% on the first day of trading, giving the firm a market value of $65bn. That is $34bn more than SoftBank, a Japanese investment group, paid for the firm in…