Executives at some of the biggest Wall Street banks said in interviews that they began planning for the rules when they were proposed last year, and they expect to be in full compliance before the regulations take effect in 2018.
But analysts paid special attention to comments from Federal Reserve Governor Daniel Tarullo, who said on Tuesday the tough rules should spur regulators to set more funding limits.
Those proposed reforms include a surcharge for the biggest global banks and possibly additional capital rules for banks that rely on risky, short-term funding.
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Fed officials also want banks to hold much more long-term debt to make it easier for regulators to unwind failing banks in a crisis.
"I call them the four horsemen of the apocalypse," said Greg Lyons, who leads the financial institutions group at the law firm Debevoise & Plimpton, in reference to the leverage rules and the three other pending requirements.
Without insight into how tough these other rules will be, experts said it's hard to put a number on how much more capital banks will have to raise, or how banks may restructure their businesses to soften the blow.
"We've got all of these pieces but ... it's not clear we know where we're going overall, or what the world looks like when we get there," said Oliver Ireland, a partner with Morrison & Foerster in Washington.
The Fed and two other bank regulators on Tuesday set leverage requirements for the biggest bank holding companies to maintain top-tier capital, such as shareholder equity, equal to 5 percent of total assets. Insured subsidiaries must meet a 6 percent ratio.
The rules, part of a global agreement to require more capital after the 2007-2009 financial crisis, would apply to JPMorgan Chase, Citigroup, Bank of America, Wells Fargo, Goldman Sachs, Morgan Stanley, Bank of New York Mellon and State Street.
But the three other rules often mentioned alongside the leverage ratio are outstanding, and less is known about how they will turn out.
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The long-term debt requirement, which would convert to equity in a crisis and serve as a capital buffer for a failed bank, and the surcharge for global banks are both priorities for international regulators as well as the Fed.