Bill Gates is the latest in a number of high-profile people who've had their personal financial information shared online by hackers.
The FBI is trying to find who is behind the website that has posted the information. Gates' personal data, including his social security number, was posted yesterday. It was the same day that Gates talked to the Washington Post about cyber security.
Hackers were able to access Gates' credit reports by answering a few simple security questions, the answers to which can all easily be found online.
The same website also posted Michelle Obama's credit report, as well as financial statements belonging to Vice President Joe Biden, and actors Ashton Kutcher and Mel Gibson.
However, hacking and identity theft don't just happen to famous people. You could also be a target.
Security experts say the best way to protect yourself is limiting the amount of personal information you post online, including on your social media profiles.