Total trading revenue at the five biggest Wall Street banks -- including JPMorgan, Citigroup, Goldman Sachs Group Inc., Bank of America Corp. and Morgan Stanley -- may have dropped 4.4 percent to $21.7 billion in the second quarter, compared with the same period last year, and 17 percent from last quarter, Kotowski said. Trading accounted for almost a quarter of the firms' revenue last year.

"Investors are likely to be disappointed with second-quarter results for the universal banks as the combination of challenging trading and interest rate environment is likely to result in declining revenue trends," KBW Inc. analysts led by David Konrad wrote in a June 29 research note. They projected an 8 percent drop in industry revenues from last year.

Mergers And Acquisitions

JPMorgan and Citigroup may counter declines in trading revenue with an increase in fees from investment banking, which includes managing sales of equities and bonds as well as advising on mergers and acquisitions.

James Staley, JPMorgan's investment-banking chief, may increase revenue from those businesses by 28 percent to $1.8 billion, according to Moshe Orenbuch, a New York-based analyst at Credit Suisse AG. Citigroup's investment-banking unit, run by Ray McGuire, may also post a 28 percent gain to $865 million, estimates provided by Orenbuch show.

Citigroup CEO Vikram Pandit, 54, aims to mitigate declining U.S. revenues by expanding abroad, according to Richard Staite, a London-based analyst with Atlantic Equities LLC. Citigroup got 62 percent of its first-quarter revenue outside North America.

Revenue from Latin America, Asia, Europe, the Middle East and Africa may climb 7.7 percent to $4.67 billion at Citigroup's regional consumer bank while dropping 10 percent to $3.31 billion in North America, according to Staite.

Plunge In Revenue

The lender's Citi Holdings unit, which includes assets Pandit tagged for sale in January 2009, may post a $1.59 billion plunge in revenue, accounting for more than half of the bank's overall decline, according to Staite.

Citigroup's increased lending aboard has been accompanied by higher expenses, which are eroding profit, Staite said in a phone interview. Consumer banking income from continuing operations in international markets may fall 7.1 percent to $1.01 billion in the second quarter compared with the same period last year, Staite's estimates show.