Account holders can rest easy with Amex. Your American Express High Yield Savings Account is FDIC-insured up to $250,000 per depositor, and you can increase your coverage amount by adding beneficiaries to your account. The FDIC certificate number for American Express National Bank is 27471. It's a good idea when choosing to open an account with a new financial institution to see if their website or documentation says "member FDIC." In the case of a credit union, you want to look for NCUA insurance, which is similar.