NEW YORK - Most of the largest United States banks passed their annual stress test, according to the Federal Reserve, in a conservative report card that underscored the recovery of the financial sector but called out a few laggards, including Citigroup.

The Fed announced the results in an earlier-than-expected release on Tuesday.

JPMorgan Chase pulled the trigger, announcing its own glowing marks before the Fed's release, and helped lift the stock market.

But the failing grade for Citigroup, the nation's third-largest bank, was a shock.

Going into the tests, some analysts felt it had a better chance of a positive surprise than any other financial institution.

The Fed said on Tuesday that 15 of the 19 banks tested would have enough capital, even if they suffered a financial shock that would see unemployment hit 13 per cent and housing prices drop 21 per cent.

The results paved the way for many of the passing banks to announce highly anticipated plans to boost dividends and buy back stock.

The outcome showed a middle-of-the-road approach.

The Fed failed enough banks to give the tests credibility and to elicit an industry outcry about the tests being too tough, but it reassured markets that the US banking industry is generally healthy.

"Overall, we can't complain that these tests weren't rigorous enough, and it's good to know that most banks would at least survive another global financial meltdown," said Mr Paul Ashworth, chief US economist at Capital Economics in Toronto.

MetLife, the largest life insurer in the US, was also among the four financial institutions that failed the exam, which applied worst-case stress scenarios looking out through the end of 2013. Ally Financial and SunTrust were also at the bottom of the heap.

Among the winners was JPMorgan, which has been agitating for regulators to loosen the handcuffs on the ability of banks to raise dividends and buy back stock.

The Fed uses the annual stress tests to give the markets a window into the health of the US banking industry, and also determine if individual banks are strong enough to reduce their capital buffers.

Bank of America, the nation's second-largest bank, passed the Fed's test, but it did not ask for a dividend increase or to buy back shares. Last year, the Fed rejected the bank's request for a dividend hike, in a major embarrassment for chief executive Brian Moynihan.

JPMorgan, in a surprise to markets, announced around 3pm EDT that the Fed had given it permission to raise its dividend by 20 per cent and spend as much as US$12 billion (S$15 billion) buying back stock this year.

The news helped the US stock market post its best day this year.

The Fed had been scheduled to release the test results after markets closed today.

Regarding the outcome of the tests, the Fed official said the capital positions of US banks have improved substantially in the last three years.

Regarding the outcome of the tests, the Fed official said the capital positions of US banks have improved substantially in the last three years.