The most eagerly awaited initial public offering of the year in the US was launched on Thursday with Google shares jumping by more than 18 per cent in the first day of trading.

Investors interested in Google, but unwilling to take part in the auction process used to allocate shares, appeared to be piling in as trading began. The shares, after being priced at $85 on Wednesday night a far cry from the $135 that marked the top of the expected range initially set by the company opened at $100 at 11:55am, and traded as high as $104.06, or 22.4 per cent higher, before closing at $100.34, with a gain of 18 per cent, giving a market capitalisation of $27.22bn.