Big banks including JPMorgan Chase and Goldman Sachs had just finished taking victory laps after a blockbuster quarter when concerns emerged from an obscure corner of Wall Street, sending a collective shiver through global finance.Regional bank Zions late Wednesday disclosed a near total wipeout on $60 million in loans after finding "apparent misrepresentations" from the borrowers. The next day, peer Western Alliance said that it had sued the same borrower, a commercial real estate firm called the Cantor Gr ...