A signboard of Citibank is pictured over a traffic sign at its branch in Tokyo, February 23, 2009. Citigroup is in talks that could result in the U.S. government increasing its stake in what was the country's most valuable bank, a source said, and the Wall Street Journal said taxpayers could own as much as 40 percent of the ailing lender's common stock. REUTERS/Kim Kyung-Hoon (JAPAN)