Microsoft (Nasdaq: MSFT), the world's biggest software company, is getting a facelift at 37. The company unveiled a new corporate logo Thursday that uses colosfor the first time: red, green, blue and yellow in squares next to the company name .

The change comes as the Redmond, Wash., company is on the verge of shipping its Windows 8 OS, scheduled for late October. The logo change is intended to signify the "future, a newness and freshness," said Jeff Hansen, general manager of brand strategy.

Adding colors is intended to add "diversity," he added. It replaces a logo dating from 1997. Microsoft was founded in 1975 and had four previous logos.

Microsoft shares fell 29 cents to $30.25 in afternoon trading, valuing the company at $253.6 billion.