WASHINGTON — Five of the biggest U.S. banks have six months to get disaster plans in shape. That’s the message regulators issued Wednesday after giving the banks failing grades for strategies they would deploy if they went into bankruptcy.

JPMorgan Chase, Bank of America, Wells Fargo, Bank of New York Mellon and State Street Bank were cited by the Federal Reserve and the Federal Deposit Insurance Corp. for “living wills” that are “not credible” or insufficient for an orderly restructuring if needed. The banks were required to submit the plans outlining how they would reshape themselves in the event of failure.The government exercise is aimed at avoiding a repeat of the taxpayer bailouts of “too-big-to-fail” banks during the 2008 financial crisis. Having to salt away bigger capital reserves against unforeseen losses could eventually cut into banks’ profitability.But for now, the regulators’ thumbs-down represents merely a ripple for a mostly robust U.S. banking industry. They wouldn’t face any government sanctions for at least six months.The five banks, with a total of about $5.6 trillion in assets, were among eight Wall Street behemoths whose plans were evaluated. The other three banks — Citigroup, Goldman Sachs and Morgan Stanley — got less-than-glowing reports from the regulators, though not as severe.The big banks have been working on their plans for four years. The regulators gave them an Oct. 1 deadline to fix the problems or face possible “more stringent” requirements. That could include ordering the banks to beef up capital cushions against unforeseen losses. If the regulators still weren’t satisfied, banks could be forced to sell off assets — but not before two years.Investors view the banks’ shortcomings in their “living wills” mainly as a housekeeping problem rather than a sign of fundamental financial weakness.