The Treasury plans to sell about one-fifth of insurer AIG through a stock offering in the first half of 2011, an important test of the governmen’s ability to profitably exit one of its most controversial bailouts. AIG and the Treasury would both sell stock in the offering, which could total $10bn to $15bn, sources said. That would place it among the largest secondary share offerings in history. AIG got a $182.3bn taxpayer-funded aid package during the financial crisis. An offering could come as early as March, but details have not yet been decided. Analysts said the proposed sale of 20 per cent of the company was a cautious first step toward yanking the insurer off government life support.