US banks face the group dining conundrum. When one gourmand plumps for foie gras while another opts for soup, the bill is split regardless. Similarly, large financial institutions will be picking up the tab for dealing with systemically important peers that gorge themselves on risky activities, under draft legislation announced this week. Diners, unsure what others will choose, can either set down some rules or just order extravagantly themselves. For banks the latter is undesirable, as those paying for failures appear to have little scope to protect themselves.

Indeed, the possible size of the bill, paid after failures rather than through premiums beforehand, is unknown. Large commercial bank failures have recently cost about a quarter of their assets, based on the estimated hit to the Federal Deposit Insurance Corporation’s fund after assets are sold and investors wiped out. But managing the demise of a complex financial behemoth, rather than a bog-standard deposit-taker, is a different challenge altogether.