BUZZ-Petrobras SA: Citigroup Global Markets upgrades to buy
** U.S-listed shares of Brazil's state-run oil company up 5.1 pct at $11.04 premarket
** Citigroup Global Markets analyst Pedro Medeiros upgrades to "buy" from "neutral"
** Medeiros says in a note the stock's 54 pct drop in the past three months left it trading at attractive multiples
** Stock trades at forward price-to-earnings ratio of 7.32, compared to 13.46 for the sector
** Of the 15 analysts covering the stock, 1 rate it "strong buy", 10 a "hold", 4 a "buy", according to Thomson Reuters data
** Analyst cuts price target to $13 from $17; median price target on the stock is $19.35
** Up to Monday's close, stock had fallen 23.8 pct this year
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