* Lehman bankruptcy sparks risk aversion
* Yen rallies broadly, U.S. stocks slide (Recasts; adds comment, details, updates prices, changes byline)
By Nick Olivari
NEW YORK, Sept 15 (Reuters) - The U.S. dollar fell against the euro on Monday amid increased risk aversion after Lehman Brothers Holdings Inc <LEH.N> filed for bankruptcy protection, spurring a stock market sell-off, while the yen rallied on the unwinding of carry trades.
The dollar had managed to hold gains against the euro for most of the New York session, but as Wall Street benchmark indexes extended losses in late trading, the U.S. currency fell in their wake.
Investor attention is now focused on American International Group <AIG.N>, once the world's largest insurer, for clues as to whether there are other companies that may need to raise capital to cover mortgage-related losses.
Treasury Secretary Henry Paulson said on Monday the U.S. financial system remained sound despite current stresses and he was prepared to take further actions if necessary to maintain stability. For details, see [
]"So far, the efforts of the US government have failed to bring any stability to the financial markets," said Kathy Lien, director of currency research at Global Forex Trading.
The euro <EUR=> rose 0.6 percent to $1.4308, though it remained off its session high of $1.4479.
The ICE Futures U.S. dollar index <.DXY>, which measures the dollar's performance against a basket of six currencies, was little changed at 78.311 after climbing as high as 79.360.
CARRY TRADES UNWOUND
The rise in risk aversion led investors to unwind carry trades, which are funded by borrowing in the low-yielding yen.
The dollar fell to 104.55 yen <JPY=> at one stage, according to Reuters data. It was last down 2.9 percent at 104.83, while the euro <EURJPY=> dropped 2.2 percent to 150.00 yen.
Seen as a safe haven, the Swiss franc rose against the dollar, which fell 1.9 percent to 1.1092 francs <CHF=>.
Lehman's bankruptcy protection filing made it the largest and highest-profile casualty of the global credit crisis.
At the same time, the market was also digesting news that Bank of America <BAC.N> had agreed to buy Merrill Lynch <MER.N> and the Federal Reserve would accept equities in exchange for cash loans for the first time in its history.
While Wall Street stocks were volatile and 10-year U.S. Treasury credit default swaps hit a record wide, the foreign exchange market was not yet fearing a U.S. financial system meltdown, analysts said.
The high-yielding Australian and New Zealand currencies fell sharply versus both the U.S. dollar and the Japanese yen.
The uncertainty was so high that major central banks around the world, including the European Central Bank, Bank of England and Bank of Japan, said they stood ready to help soothe markets.
There is also speculation that the Federal Reserve, which holds its regular policy meeting on Tuesday, may cut interest rates again.
Fed funds futures are pricing in a 76 percent chance of rates dropping to 1.75 percent from 2.0 percent at the September meeting <FEDWATCH>. (Reporting by Nick Olivari and Lucia Mutikani; editing by Gary Crosse)