US bank Citigroup warned Tuesday that trading revenues were down 15 percent in the first quarter from a year ago, underlining market troubles amid worries about the global economy.

Revenues from investment banking, which includes financial services to companies, mergers and acquisitions, and initial public offerings, were down 25 percent so far in the same period, John Gerspach, Citigroup’s chief financial officer, said at a conference held by RBC Capital Markets.

Revenues from trade in fixed-income instruments, currencies and commodities (FICC), the cash cow for banks after the 2008 financial crisis, have hit a tough patch in recent quarters.

In addition to the growing weakness in the global economy, FICC trading has been hit by stricter regulation on speculation, for example, with limits on proprietary trading, when banks trade using their own money.

The New York-based Citigroup is scheduled to report first-quarter earning on April 15.

Citigroup shares were down 2.9 percent at $41.38 in afternoon trade.