For years, Wells Fargo employees secretly issued credit cards without a customer’s consent. They created fake email accounts to sign up customers for online banking services. They set up sham accounts that customers learned about only after they started accumulating fees.

On Thursday, these illegal banking practices cost Wells Fargo $185 million in fines, including a $100 million penalty from the Consumer Financial Protection Bureau, the largest such penalty the agency has issued.

Federal banking regulators said the practices, which date back to 2011, reflected serious flaws in the internal culture and oversight at Wells Fargo, one of the nation’s largest banks. The bank has fired at least 5,300 employees who were involved.

In all, Wells Fargo employees opened roughly 1.5 million bank accounts and applied for 565,000 credit cards that may not have been authorized by customers, the regulators said in a news conference. The bank has 40…