Since July 20, when Microsoft announced plans to buy back up to $20 billion worth of its stock in one swoop, shares have climbed 7.5 percent as of today's close.

The stock gained 8 cents today to hit $24.70, a nickel below the upper end of the price range Microsoft said it will pay to repurchase its shares. Twenty billion would buy 808,080,808 shares at $24.75, reducing Microsoft's float by about 8 percent and adding about 5 or 6 cents per share to forecast fiscal 2007 earnings as income is spread across fewer shares.

The tender offer closes at 11:59 p.m. Eastern Time on Thursday.