What's Shaking: Monday's Early Movers

Take a look at some of Monday morning's early movers:

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Citigroup , Bank of America - Goldman Sachs upgrades Citi to "buy" from "neutral", while downgraded B of A to "neutral" from "buy". The firm sees a clearer path for Citi to return capital to shareholders, while anticipating higher execution risk for Bank of America over the next 12-18 months.

Morgan Stanley - Goldman has upgraded the stock to a "conviction buy" from "neutral".

U.S. Airways - Delta Air Lines is considering the possibility of a takeover bid for its rival, according to the Wall Street Journal. Delta is also said to be considering a similar move for American Airlines parent AMR , currently operating under bankruptcy protection.

Boeing , Lockheed Martin - South Korea invites both companies to bid for its $7.4 billion next-generation fighter jet program.

Exxon Mobil – The oil giant is selling the majority share of its Japanese refining and marketing unitto Japan refiner Tonen for $4 billion.

Staples - Goldman Sachs has downgraded the office products retailer's stock to "sell" from "neutral", expecting sluggish demand in the company's core supplies market.

Wendy’s - The restaurant operator is set to hold its annual Investor Day today , at which it will release its preliminary 2011 results.

Kellogg - JPMorgan Chase has cut its rating on the cereal maker to "neutral" from "overweight" , saying the company's earnings are likely to disappiont over the next two years. It's also cut its price target for Kellogg to $48 from $62.

El Paso – The WSJ reports that a group led by private equity firm Apollo Global Management is in late-stage talks to acquire El Paso’s oil exploration unit for about $7 billion.

D.R. Horton - The homebuilder's shares have been downgraded to "market perform" from "outperform" at Keefe, Bruyette & Woods.

Thomas & Betts - Switzerland’s ABB agrees to buy the U.S.-based electrical components maker for $3.9 billion in cash, or $72 per share. The price represents a 24% premium over Friday’s closing price.

Express Scripts - The pharmacy benefits manager will be raising out-of-pocket costs for customers who use Pfizer’s cholesterol drug Lipitor, following the introduction of generic versions late last year.

Amylin , Alkermes – The Food and Drug Administration has approved the diabetes drug Bydureon, developed by a partnership between the two companies. Bydureon is designed to treat type 2 diabetes.

Regeneron Pharmaceuticals - The stock has been upgraded to "buy" from "netural" at Bank of America Merrill Lynch, with the price target increased to $105 from $74.

Momenta Pharmaceuticals - The stock is replacing HealthSpring in the S&P SmallCap 600 this week, following the completion of HealthSpring's deal to be acquired by Cigna .

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