Microsoft posted its first quarterly loss in its 26 years as a public company on Thursday, mainly due to its struggling online ad business, at a time where the company is prepared for one of the biggest product updates in its history, Windows 8.

Microsoft announced quarterly revenue of $18.06 billion for the quarter ended June 30, 2012. Operating income and loss per share for the quarter were $192 million and $0.06 per share.

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.

"We delivered record fourth quarter and annual revenue, and we're fast approaching the most exciting launch season in Microsoft history," said Steve Ballmer, chief executive officer of Microsoft. "Over the coming year, we'll release the next versions of Windows, Office, Windows Server, Windows Phone, and many other products and services that will drive our business forward and provide unprecedented opportunity to our customers and partners."

"The combination of solid revenue growth and rigorous cost discipline drove double-digit operating income growth for the quarter, adjusting for the goodwill impairment and deferred revenue," said Peter Klein, chief financial officer of Microsoft. "We are focusing our resources in strategic areas that will deliver shareholder value and long-term growth opportunities."

"We expect Windows revenue to be roughly in line with the PC market" which it said was flat in the last quarter and is expected to continue that way in the three months through September, Peter Klein told analysts.

For Microsoft's fiscal year 2012, the company's revenue, operating income, and earnings per share were $73.72 billion, $21.76 billion, and $2.00 per share.

Microsoft's Server & Tools business revenue grew 13% for the fourth quarter and 12% for the full year. Windows Server 2012 will be available this September.

The Microsoft Business Division revenue grew 7% for the fourth quarter and 7% for the full year reflecting continued momentum in Office 2010 sales. Microsoft says Office is now installed on more than 1 billion PCs around the world. Earlier this week, the company announced the customer preview of the new Microsoft Office.

The Windows & Windows Live Division revenue declined 13% for the fourth quarter and 3% for the full year. Adjusting for the impact of the Windows Upgrade Offer, Windows Division non-GAAP revenue declined 1% for the fourth quarter and 1% for the full year. Windows 7 adoption continued with more than 50% of worldwide enterprise desktops now running Windows 7. The next version of Windows will release to manufacturing this August and will become generally available October 26, 2012.

The Online Services Division revenue grew 8% for the fourth quarter and 10% for the full year reflecting growth in our search business. Bing organic U.S. search market share was 15.6% for the month of June 2012, up 120 points from the prior year period.

The Entertainment and Devices Division revenue grew 20% for the fourth quarter and 8% for the full year primarily reflecting the addition of Skype. Xbox has now been the top-selling console in the U.S. for 18 consecutive months. During the year, Xbox launched new television and video partnerships for Xbox LIVE, and announced Xbox SmartGlass, which connects phones, PCs, and tablets with the Xbox 360 console to enable more interactive and engaging entertainment.