Apple briefly became the largest company in the US when its market value rose to $341.5bn (£210bn) last night.

It overtook oil giant Exxon's value of $341.4bn (£209.9bn) before slipping back into second place before the markets closed. Exxon's annual revenue is around four times that of Apple's, reports Reuters.

The news comes after another volatile day on the stock markets after the downgrading of the US credit rating last week. However, it does symbolise an economic shift driven by technology with the traditional old guard being challenged by new contenders. Exxon has been the most valuable US company for the last five years.

Apple's value ended at $346.7bn (£213.1bn) and Exxon's at $348.3bn (£214.1bn). Last month, Macworld reported that Apple had more in the way of liquid assets than the US government.