Citigroup (C - Get Report)  posted better-than-expected results for the first quarter as a cut in the U.S. bank's effective corporate tax rate helped to offset a fall in stock-trading revenue.

Net income climbed by 2% from a year earlier to $4.71 billion, the New York-based bank said Monday in a press release. Earnings per share were $1.87, beating Wall Street analysts' average estimate of $1.80.

The effective tax rate for the quarter dropped to 21% from 24% in the first quarter of 2018. 

The bank cited "momentum" in areas including credit cards, providing banking services to corporations and investment banking, which is the business of advising on corporate mergers and underwriting stock and bond offerings.  

"Both our consumer and institutional businesses performed well, and we saw good momentum," CEO Michael Corbat said in the press release. 

Stock-trading revenue fell by 24% from a year earlier to $842 million, while fixed-income revenue increased by 1% to $3.45 billion, according to the bank. 

The drop in the stock business was attributed to "lower market volumes and client-financing balances," according to the press release. 

The gain in fixed-income markets came from strength in government bonds and "spread products," which includes corporate bonds and asset-backed bonds whose prices depend on investor perceptions of the issuer's ability to repay the borrowed money. 

Revenue in Citigroup's global consumer-banking business was roughly flat with the prior year's levels, at $8.45 billion. 

The stock fell 0.4% to $67.16 in trading Monday.

Citigroup got a benefit during the quarter from an unexpected $4 million reduction in its reserves for future loan losses. The bank had been expected to boost the reserves by $195 million, according to analysts at the brokerage firm Keefe, Bruytette & Woods. 

Net interest income came in below estimates, with average loans increasing at an annualized rate of just 2.2% during the first quarter, versus an expected 4.4% growth rate, the KBW analysts wrote in a note to clients. 

"The quarter was mixed," the analysts wrote.  

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