The building of a Citibank branch is seen at Paulista Avenue in Sao Paulo's financial center, Brazil, in a February 19, 2016 file photo. REUTERS/Nacho Doce/Files

It's the sharpest drop among the big U.S. banks reporting so far. A fall in trading and investment banking revenue hurt Citigroup, but the results beat estimates. Fred Katayama reports.

Quarterly profit at Citigroup plunged 27 percent - the sharpest drop among the big American banks reporting so far. Revenue fell 11 percent. The culprits: lower volumes slammed trading revenue in fixed-income and equities, and weak activity dug into investment banking revenue.

Citigroup, which generates half of its revenue internationally, also suffered from weakness in overseas markets, especially Latin America.

But Citigroup's profit and revenue beat analysts' estimates. The stock, which is down 13 percent this year, rallied in early trading.

These results come as Citi continues its drive to cut costs and sell assets to simplify its structure.

RBC Capital Markets analyst Gerard Cassidy said, "Citi's turnaround efforts are bearing fruit."

Just two days ago, Citi was the only big bank to pass U.S. regulators' tests on dealing with a potential bankruptcy.