You can get all 3 credit reports at www.annualcreditreport.com.
Some possibilities are:
- A mistake by one credit bureau (if not listed on all 3). You can contact the one credit bureau with the wrong info and ask them to investigate.
- You are an authorized user or co-signer on someone else's account.
- Identity theft.
You can call Amex and ask them to explain. There is a $5000 credit line that showed up on my credit report one day, so I called the bank and it turns out to be the overdraft protection on my Dad's checking account which I had just been made a joint owner of. Amex may not tell you the name of the cardholder if you don't know it, but they may be able to help you explain that it is (or is not) something you know and forgot about.
If it turns out to be legitimately fraudulent, you will need to file a report with Amex security department.
