A Citibank sign in front of one of the company's offices in California.

Jefferies upgraded Citigroup's stock to buy from hold on Friday, saying the bank is headed toward revenue growth this year, as well as added benefits from growth in its Latin America business.

"We upgrade ... given above consensus EPS estimates, a better understanding of the important [Latin America] story, and a still-attractive valuation," Jefferies said in a note to investors. "We believe '19 will show better rev. growth, stable costs/credit, and [over $20 billion in] capital return."

Jefferies expects Citi will see improving revenue "growth in U.S. branded credit cards as customer mix improves and past headwinds abate." Jefferies also said Mexico's banking business will deliver better returns for Citi "after a few years of heavy investments."

"We recently met with Jane Fraser, CEO of Latin America," Jefferies said. "[In that region] the pace of investment spending growth should begin to bend, with platform upgrades helping efficiency, new digital branches/ATMs offering better self-service options, and more partnering with external investments/insurance providers,"

Citigroup shares initially rose in premarket trading but ended the day down 0.3 percent at $64.14 a share. Jefferies has a $73 price target on Citi's stock.