U.S. bank regulators on Tuesday officially upped the amount of excess assets the nation’s eight largest banks must hold to cover potentially bad loans or soured investments. In a memo, the Federal Reserve estimated that the new rule would force the banks to raise $68 billion by the end of 2017, when the rule would go into place. The rule was jointly approved by the Federal Reserve, the FDIC, and the Office of the Comptroller of the Currency.

The Fed specifically cited “too big to fail” as one of the reason it thought the largest banks should be required to hold more capital. The Fed has recently released a number of studies that suggest the largest banks in the U.S. get an unfair advantage, though not as large as some think.

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Regulators have been tinkering with bank capital requirements for the past few years, and they have already set the amount of money that banks have to hold to cover potential losses from their riskier loans and investments. The new rule sets the so-called leverage ratio at 5% of all banks’ loans and investments, which is less than the ratio of excess assets banks must hold against their riskiest loans.

International rules require large banks to have a leverage ratio of 3%. So the U.S.’s new 5% rule is stricter. But it’s down from the 6% that regulators were considering a year ago. And it’s still far less than the 15% that some bank critics have called for.

And while $68 billion is a lot of money, the nation’s eight largest banks, which includes JPMorgan Chase (JPM), Bank of America (BAC), Citigroup (C), and Wells Fargo (WFC), shouldn’t have a hard time coming up with the funds. Collectively the banks, which also include Goldman Sachs (GS), Morgan Stanley (MS), Bank of New York (BK), and State Street (STT) earned just over $80 billion last year. Repeat that performance, and $68 billion is roughly a quarter of what the big banks will earn by the time the rule goes into effect.