Microsoft stock climbed 4 percent Thursday, closing at $31.29 — the highest it’s been since April 2010.
The climb comes after a report that S&P is likely to increase its weighting in the S&P 500, according to Bloomberg.
The gain also comes ahead of the consumer preview release of Windows 8, set for Feb. 29. Windows 8 is Microsoft’s big overhaul of its flagship operating system. It is being designed to run on both PCs and tablets.
Last week, Windows President Steven Sinofsky wrote a lengthy blog post detailing Windows 8 will look like on devices — mainly tablets — running on ARM technology.