Microsoft has made its first-ever quarterly loss after it wrote off some of the value of its online advertising business.
The company wrote down by $US6.2 billion the value of aQuantive which had failed to bring the profits expected, the BBC reports.
That led to a $US492 million loss in the three months to the end of June compared with a profit of $US5.9 billion a year ago.
Microsoft took over aQuantive in 2007, paying $US6.3 billion, but the division struggled to compete with rival Google.
Microsoft is doing well in other areas, despite the decline in popularity of its Windows operating system, which dominated the personal computer market for years.
Revenue for the three months to June rose by 4% to $US18.06 billion.
The company had not made a loss since it joined the stock market in 1986.