A punishing rotation out of Japan thrashed shares of the country’s banks Monday, sending the Topix Banks index tumbling 17%. Not even during the 2008 financial crisis, the 2020 pandemic meltdown, or the "Black Monday" crash of 1987 did Japanese bank stocks fall so hard. Japan's largest bank, **Mitsubishi UFJ Financial Group**, or MUFG, plunged 18%, its largest one-day tumble ever.