What bank runs E-Trade?

Could you clarify for me which bank operates or is affiliated with E-Trade? I'm aware that E-Trade is a well-known online brokerage and financial services company, but I'm not sure if it's owned or operated by a specific bank. Perhaps there's a partnership or ownership stake held by a banking institution, but I'd like to know the details. Is there a specific bank that runs or controls E-Trade, or does it operate independently?