Citigroup, HSBC, Santander, Royal Bank of Scotland and Zions Bank are all facing questions about their ability to ride out another calamity in the financial markets.

On Wednesday, the Federal Reserve said the five big banks need to resubmit their proposals to pay out billions of dollars to shareholders because of weaknesses in their capital plans. The other 25 banks subject to the review were given the thumbs up to move ahead with plans to increase their dividend payouts, which analysts have pegged at about $75 billion in total.

In the aftermath of the financial crisis, regulators insisted that banks sock away enough capital — cash, investor equity and other assets — to cushion against losses and stave off future taxpayer bailouts. Congress mandated that regulators give banks an annual checkup and granted the authority to stop banks from paying out capital.

As an improving economy and deep cost cuts bolster profits, banks have been eager to lavish investors with excess capital in the form of dividends or share buybacks. Regulators have remained cautious about capital planning.

“With each year we have seen broad improvement in the industry’s ability to assess its capital needs,” Fed Governor Daniel Tarullo said in a statement. “However, both the firms and supervisors have more work to do as we continue to raise expectations for the quality of risk management in the nation’s largest banks.”

While the Fed praised the progress that Citigroup has made in improving its risk management, the central bank was less ebullient about the bank’s “ability to project revenue and losses under a stressful scenario.” The Fed said the bank had failed to make “sufficient” improvements in areas that regulators had previously said needed work.

Citigroup was the largest U.S. bank to have its capital plan rejected, a blow for an institution that has fought hard to reduce expenses and mitigate risks after the crisis.

“Needless to say, we are deeply disappointed,” Citigroup chief executive Michael Corbat said in a statement. “We will continue to work closely with the Fed to better understand their concerns so that we can bring our capital planning process in line with their expectations.”

In the case of British banking giants HSBC and Royal Bank of Scotland, the Fed was concerned about the “inadequate governance and weak internal controls” of their American operations. Meanwhile, the central bank rebuked Madrid-based Santander Bank over “widespread deficiencies” in such areas as risk management at its U.S. arm.

A senior official at the Fed said the rejection means the lenders will have to keep dividend payments to their European parent companies at current levels.

Utah-based Zions had its capital plan rejected because it fell short of the Fed’s minimum 5.5 percent common equity tier 1 capital ratio, a measure of balance sheet strength. That means Zions would have trouble lending to customers in the face of a severe downturn.

All five banks have 90 days to resubmit their plans for approval, though they can continue to distribute dividends and buy back stock in the interim at current levels.

Overall, U.S. banks have made tremendous strides in squirreling away capital since the government began its annual reviews in 2009. According to the Fed, the aggregate common equity ratio of the 30 banks examined this year has more than doubled from 5.5 percent in the first quarter of 2009 to 11.6 percent in the last quarter of 2013.

All but two of the 30 banks, which hold 80 percent of all U.S. assets, are expected to raise capital from the second quarter of this year through the first quarter of 2015. The Fed would not disclose the names of those two firms.

Wednesday’s report arrived a week after the Fed issued the results of “stress tests,” the first half of the two-part bank checkup that examines whether institutions can withstand market shocks. It was clear from those results that Zions would likely have its capital plan rejected, since it was the only bank to fall short of the minimum ratio.

In light of the stress test results, Bank of America and Goldman Sachs reduced the amount of capital they intended to hand to investors, which allowed them to pass the Fed’s review. The banks wanted to give investors more capital than the Fed believed to be wise.