New York Stock Exchange ( NYX) climbed more than 4% after the Dutch government gave its crucial backing to the Big Board's planned $14 billion merger with Europe's Euronext exchange. Shares were trading up $4.20 to $102.25.

Citigroup ( C) surged after a Merrill Lynch analyst upgraded the bank to a buy from a hold. The analyst predicted significant 2007 revenue growth stemming from lower interest rates and said that Citigroup harbors less deal risk than its peers. Shares were up $1.03, or 1.9%, to $55.10.

MidSouth Bancorp ( MSL) gained after the Louisiana-based bank said it would pay a special dividend of 3 cents a share, along with its regular quarterly dividend of 6 cents. Shares were up $1.89, or 6.2%, to $32.50.

Sovereign Bancorp ( SOV) fell after an RBC Capital Markets analysts downgraded the stock to on a downgrade underperform from sector perform. Shares were down 18 cents to $25.46.

First Mercury Financial ( FMR) rose on news that the insurer had been added to three Russell stock indices as of the close of trading on Dec. 15. Shares were up 49 cents, or 2.2%, to $22.58.

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