Who does Bill Gates bank with?

The very wealthy rarely use only one bank. For starters, FDIC insures bank deposits only to $100,000 (temporarily raised to $250,000 through the end of 2009), so depositing more than that amount in a single bank puts your money at risk. The wealthy know the value of diversifying, so their assets are not all in cash deposits; homes, land, luxury vehicles, art, antiques, etc. are all ways to retain and grow wealth without having it in cash but still being able to liquidate quickly. I seriously doubt someone as wealthy as Bill gates uses only one bank for his cash holdings.