The sale, which would bring a profit of about $300 million to the U.S. Treasury, comes as President Barack Obama campaigns for a second term and has been forced to defend his administration's decision to use taxpayer money to prop up companies during the crisis.

The Treasury Department priced the offering at $30.50 a share, six percent above the $28.72 price needed for the U.S. government to break even on its investment in the insurer.

AIG intends to buy up to $3 billion of the offering.

The government has already sold three tranches in AIG above the break even price, putting Treasury on track to make a profit when it exits the insurer. Treasury has said it will not sell below the break even level.

The sale of 163.9 million shares of AIG stock will reduce the government's holding in the insurer to 55 percent from 61 percent. The offering is expected to close next week.

The insurer received multiple bailouts under both the Obama and Bush administrations, with the government pledging as much as $182 billion in aid. After the latest sale, the Treasury's investment in AIG will be about $25 billion.

The Obama administration has been unwinding its position in the politically unpopular financial crisis bailout programs. More than 300 small banks have yet to repay taxpayers. The administration could sell its remaining stake in AIG this year but has been adamant in saying it will not act for political reasons.

The Treasury hired over a dozen financial institutions to help coordinate and run the offering, including Citigroup Inc, Deutsche Bank Securities, Goldman Sachs, JPMorgan Securities, Morgan Stanley and Credit Suisse.

AIG shares closed up 1.62 percent at $31.34 on Friday.

The company is still not overseen by a single regulator and is expected to be slapped with a "systemically important" label from the powerful new U.S. council of regulators. The label would then subject AIG to new rules as well as supervision from the Federal Reserve.

(Reporting by Ben Berkowitz, Lauren Tara LaCapra, Rachelle Younglai; editing by Andrew Hay, Bernard Orr, Gary Crosse and Carol Bishopric)

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