Just three years after buying into AOL, Google looks to have given up on the $1 billion (£513 million) it invested, after filing a report saying the stake could be "impaired."

The US Securities and Exchange Commission filing reflects the likelihood of Google having to take a hit over the AOL investment on its next earnings report. Getting it out in the open is the first stage.

Microsoft factor

The 5 per cent stake in AOL came about in 2005 as Google sought to avoid the Time-Warner-owned operation tying up with Microsoft on advertising.

Google's declaration comes after rumours that Time Warner is planning to split AOL's web offerings from its ISP business.

Whatever the result of the filing, Google's first-half profits this year of $2.25 billion (£1.15 billion) mean there's no suggestion of financial trouble ahead for the search giant.