NEW YORK (TheStreet) --Citigroup  (C - Get Report) got a downgrade Wednesday from an analyst who overlooked its poor fourth quarter but is now worried about its exposure to weakening foreign economies that rely too heavily on short-term foreign investment.

"When a currency problem arises in multiple countries worldwide that forces dramatic changes in interest rates... banks suffer. Business in those countries weakens. Citigroup is the only U.S. based bank that is vulnerable to those trends," wrote Rafferty Capital Markets analyst Dick Bove.

Bove lowered his rating to "Sell" from "Buy," while cutting his target price to $44.50 from $57.00. Citigroup shares were down by more than 3% to $48.09, and appeared to take another leg down following the downgrade.

The Argentinean peso has been one of the hardest hit currencies in recent days, and while a recent report from KBW told investors Citigroup can manage its Argentinean exposure, the threat to Citigroup does not end there. Currencies and stock markets in several countries around the globe have tumbled this week, led by the "fragile five" of Turkey, Brazil, India, South Africa and Indonesia.

Citigroup has suffered downgrades and estimate cuts from other analysts following a weak fourth quarter showing, and indeed, Atlantic Equities analyst Richard Staite in a Jan. 24 downgrade highlighted the emerging market threat as the Federal Reserve reduces stimulus. That can cause U.S. interest rates to rise, making investment in foreign debt comparatively less attractive.

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