LOS ANGELES – Microsoft posted its first quarterly loss in its 26 years as a public company on Thursday as it declared a struggling online ad business a bust and prepared for one of the biggest product updates in its history.

The software company had warned two weeks ago that it would take a $6.2 billion charge in the April-June quarter because its 2007 purchase of online ad service aQuantive failed to help it compete with Google Inc. The amount reflected the bulk of the $6.3 billion acquisition cost.

The online ad business remains just a tiny part of Microsoft – comprising just 4 percent of its annual revenue. Most of the company's sales come from its Office suite of productivity software, Windows operating system and, increasingly, computer servers.