The federal government suffered a 63% drop in the value of an investment in American International Group Inc. within 6 weeks after the deal was made, according to the Troubled Asset Relief Program Oversight Board.

The board, which was created to oversee, TARP, says the performance of the TARP investment in AIG, New York, led to the biggest drop in any TARP deal value reported so far.

The government invested $40 billion in AIG Sept. 17. The value of the government’s stake in AIG fell to about $15 billion Nov. 10, when the stake was valued, the oversight board says.

The next biggest TARP loss involved Citigroup Inc., New York.

The value of the Citigroup TARP investment fell to $10 billion Nov. 24, from $20 billion, the oversight board says.

For every $100 invested in AIG and Citigroup, the Treasury has received assets with a value of $41, the oversight board estimates.

When the board looked at the totals for the first 10 TARP transactions, which include the AIG and Citigroup transactions, it found that the government received about $66 in assets for every $100 invested.

The analysis of TARP investment performance “raises substantial doubts about whether the government received assets comparable to its expenditures,” the TARP Oversight Board says.

“Valuation of the transactions is critical, because then-Treasury Secretary Henry Paulson assured the public that the investments of TARP money were sound, given in return for full value,” the board says.