According to the Yahoo! Insider Trades site, Bill has 917,924,402 shares of Microsoft
On 4/2/2007, Microsoft was selling for $27.74.

This means Bill Gates owns $25,463,222,911.48 worth of Microsoft stock. (That's $25.46 Billion.) This excludes many other areas of wealth and income, but is a rough guide to his major assets.

What Could be done with the Wealth of Bill Gates?

With about 7 billion people on the planet. It means that Bill could give $3.86 to every person on the entire planet and still have some change left over!

If Bill wanted to spend all his time playing Pac-Man, assuming each 25¢ game lasts 10 minutes (he isn't very good at it), Bill could play for 1,936,514.02 Years

If Bill Gates were a country his wealth would make him the 76th richest country. Just above Sri Lanka and just below the total GDP of Bulgaria $26 bn

If Bill Gates wealth was converted into $1 bills and laid end to end he could lay the money from the earth to the moon and have enough for 5 round trips. (good job he doesn’t keep it under his bed!)
If the bills were laid like a carpet (no overlapping) they could cover the size of the Vatican 586 times. (what doth a man profit if he …)

View Biography of Bill Gates

Source for information about Bill Gates Wealth

Also see: Bill Gates wealth index (a bit outdated now)