Major banks just finished reporting sluggish trading results for the first quarter last month, and now things already look bad for the second quarter.

JPMorgan Chase reported in a regulatory filing Friday that revenue from stock and bond trading will plunge about 20 percent in the second quarter from a year ago. Given that the quarter isn't even half over yet, that's not too encouraging.

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Volume and volatility have dropped in many markets, making it difficult for banks to earn money trading in them, The Wall Street Journal reports.

Trading was a major source of bank profits in the past, but regulations such as the Volcker Rule have curbed the activity.

The banks have had trouble recently trading bonds and other debt securities, interest-rate swaps, currencies and commodities, according to The Journal.

"We're in a low-volume, low-volatility environment, which is not good for markets," a senior trading executive at a large bank told the paper. JPMorgan's disclosure "is a litmus test. They're in everything."

But JPMorgan won't be the only major bank to suffer, analysts say.

“We expect that the weakness JPM is experiencing in trading-related revenues will be duplicated at other capital-markets-oriented banks," Charles Peabody, an analyst at Portales Partners, told Bloomberg News. Citigroup and Goldman Sachs are the most likely candidates to take a hit, he said.

The KBW Bank (Stock) Index has generated a total return of 19.3 percent over the past year.

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