Windows 8 is being designed to run on both tablet computers and PCs. One version of Windows 8 will run on phone-style ships instead of the Intel-style chips Microsoft has used in its software for decades.
Microsoft has previewed Windows 8 and has not announced a release date, although it's expected to be on the market in late summer or early fall.
The company is also counting on its recent $8.5 billion acquisition of Skype to help it catch up in some the hottest markets in technology and media. It wants to grow online socializing, mobile phones and digital video.
Shares of the Redmond, Wash., company gained $1.24, or 4.1 percent, to close at $31.29. During the day they peaked at $31.55, their highest price since April 2010.
Broader stock markets moved higher Thursday as well on positive signs for both the U.S. economy and a potential bailout deal for Greece. The Dow Jones industrial average, of which Microsoft is a component, picked up almost 1 percent and the S&P 500 gained 1.1 percent.