?Mideast oil state now top shareholder of largest U.S. bank. Abu Dhabi Investment Authority will become the largest shareholder in Citigroup, with a $7.5 billion capital infusion in return for 4.9 percent ownership of the bank, America's largest by assets. The Abu Dhabi Investment Authority, or ADIA, is an investment arm of the Abu Dhabi government, with an estimated $1 trillion under management. Abu Dhabi is the largest emirate in the United Arab Emirates and its capital. According to the Wall Street Journal, the investment will make ADIA the largest shareholder of Citigroup, exceeding the stake held by Saudi Prince Alwaleed bin Talal.?