American Express recently created a single sign-on for users that have both a Credit Card and High Yield Savings Account. After moving to the Open Authentication process for linking and updating accounts, Personal Savings accounts are no longer supported.
If you use the single sign-on URL to access your existing American Express Savings account, we recommend marking the account as Closed, then creating a manual account to continue tracking the balance of your account. This will preserve the historical data of your savings account. You can read more about how to mark an account as closed and create a manual account in these support articles: