AIA, the Asian unit of troubled US insurer AIG, has raised 20.5 billion US dollars in a Hong Kong share sale that is the world's third-biggest ever initial public offering, a spokeswoman said Tuesday. AIA raised 17.8 billion dollars in its share sale last month but said at the time the IPO could top 20 billion US dollars if certain options were exercised. '(The IPO) raised 20.51 billion US dollars after the exercise of the greenshoe option, which brings the total number of shares offered to about 8.08 billion,' an AIA spokeswoman told selfnews. In July, Agricultural Bank of China claimed title to the world's biggest IPO with a monster 22.1 billion US dollar offering, beating out the previous world record set by Industrial and Commercial Bank of China, which raised 21.9 billion dollars in 2006. AIA shares soared 17 percent on their first day of trading on Friday, closing at 23.05 Hong Kong dollars, well above their 19.68 dollar IPO price. The shares were trading down 0.2 percent at 22.95 Hong Kong dollars in morning trade on Tuesday. AIA's parent moved to list its Asian unit as part of a plan to repay US taxpayers after receiving a heavily-criticised 182 billion US dollar government bailout at the height of the global financial crisis. Some of those funds are to be recouped from proceeds of the AIA sale, a priority for the embattled Obama administration, which is facing rising voter anger ahead of key mid-term elections Tuesday in the United States. The US insurer was forced to look at publicly floating AIA in Hong Kong after the collapse in June of a proposed 35.5-billion US dollar sale to British insurer Prudential. 