NEW YORK, Nov. 24 (Xinhua) -- Wall Street posted the largest two-day rally since 1987 on Monday after the U.S. government rescued Citigroup late Sunday night.

The U.S. Treasury Department decided to inject 20 billion U.S. dollars to the second largest U.S. bank by assets, after backing the bank with 25 billion U.S. dollars last month under the Troubled Asset Relief Program.

    Citigroup also received 306 billion dollars of U.S. government guarantees for troubled mortgages and toxic assets.

Traders work on the floor of the New York Stock Exchange, Nov. 14, 2008

    Citigroup's stock jumped 58 percent after dropping 60 percent last week. Other financial giants like JP Morgan Chase & Co., Bank of America Corp and Goldman Sachs jumped more than 21 percent sending the S&P 500 up to a record gain.

A traffic light is seen in front of a Citibank branch in New York Oct. 6, 2008.

Also on Monday, President-elect Barack Obama unveiled his economic team pick to shore up financial markets and tackle the worst financial crisis since the Great Depression in 1930s.

    The Dow Jones average rose 396.97, or 4.93 percent, to 8,443.39.The Standard & Poor's 500 index advanced 51.78, or 6.47 percent, to 851.81, and the Nasdaq composite index rose 87.67, or 6.33 percent, to 1,472.02.