Google stock is once again at and all time high on rumours that the company is about to invest 1 billion dollars (£564m) for a 5% stake in AOL.

The news, which broke over the weekend by a number of news sources suggested that Google had beaten Microsoft in the bidding war to secure a partnership with AOL, the largest single source of Google's advertising revenue.

Microsoft, which has launched its own search technology through MSN and, was hoping a deal with AOL would help it close the gap on Google and Yahoo.

AOL's use of Google's search engine means that its 26 million users across the globe provide a big audience for Google's pay-per-click advertising.

The news of the negotiations pushed Google's share price over $430, and more than quadruple their original flotation price of $85 18 months ago.

The deal, which could be announced tomorrow, will provide Google with access to Time Warner's film and television library opening up the possibility of the search engine offering a movies on demand service.