WASHINGTON (AP) — Federal regulators are requiring big banks to keep enough high-quality assets on hand to survive during a severe downturn, the latest move under congressional mandate to lessen the likelihood of another financial meltdown.

The Federal Reserve adopted rules on a 5-0 vote Wednesday that will subject big U.S. banks for the first time to so-called “liquidity” requirements. Liquidity is the ability to access cash quickly. The Federal Deposit Insurance Corp. and the Treasury Department’s Office of the Comptroller of the Currency adopted the rules later in the day.