The lucky country’s banks may have finally run out of good fortune. Australia’s nearly three decades of uninterrupted growth have made its top lenders among the world’s most profitable. Recent high-profile scandals, though, have dented their image. The banks could have more than just an impending slew of regulatory fines to worry about.
The $530 million fine levied on Commonwealth Bank of Australia on Monday for money-laundering-rule breaches—the biggest civil corporate fine ever proposed Down Under—certainly isn’t a good...