The scandal engulfing Wells Fargo toppled its chairman and chief executive on Wednesday, as John G. Stumpf announced his departure from the company, effective immediately.

The move was a swift and stunning fall for an executive whose bank made it through the 2008 financial crisis relatively unscathed, only to be undone by a sham-account sales scandal that pervaded its community banking division and percolated under the surface for years.

It was an extraordinary moment even in the banking industry, which has been bedeviled by criticism and regular scandals since the financial crisis. Despite the industry’s many troubles, relatively few banking chiefs have stepped down under outside pressure.

But Wells Fargo’s transgressions were unusually blatant and straightforward, which contributed to the still-mounting public outcry. This time, there were no exotic financial instruments, complicated trades or complex mortgage trickery. The bank’s misdeeds were fundamentally simple: Under intense pressure to meet aggressive sales goals, employees created sham accounts using the names — and sometimes, the actual money — of the bank’s real customers. And in some cases the customers did not discover the activity until they started accumulating fees.