By agreeing to purchasing a $7.5 billion stake in the faltering banking giant Citigroup, the secretive, government-controlled Abu Dhabi Investment Authority is breaking with tradition. As the largest sovereign wealth fund in the world, with assets estimated at $650 billion, it poured money in the past into low-return, low-profile investments or small emerging market deals, unlike its flashy emirate neighbor, Dubai. But a falling dollar and a growing cash pile are spurring Abu Dhabi to change strategy, according to analysts, economists and deal makers, who said that more big-ticket deals might be ahead. Flush with cash from its oil exports, Abu Dhabi turned to Wall Street, using a complicated transaction late Monday to buy 4.9 percent of Citigroup, acquiring high-yield, convertible stock that must be exchanged for common stock between March 2010 and September 2011. Abu Dhabi is the largest oil producer of the seven United Arab Emirates and is eager to spend its petrodollars. ‘They’re watching them depreciate, and that’s driving their anxiety,’ said Marc Ginsberg, a former U.S. ambassador to Morocco who has worked with other emirates. Abu Dhabi also has an interest in making sure the U.S. economy does not slow […]