Too big to fail is likely to prove a costly epithet for the world’s biggest banks as regulators demand they increase holdings of debt securities to cover losses should they collapse. The shortfall facing lenders from JPMorgan Chase & Co. (JPM) to HSBC Holdings Plc could be as much as $870 billion, according to estimates from AllianceBernstein Ltd., or as little as $237 billion forecast by Barclays Plc.