NEW YORK — The Federal Reserve resisted a cut in interest rates yesterday and then forged a plan to take over American International Group Inc. and rescue the insurance giant from the brink of bankruptcy with an extraordinary $85 billion loan.

The moves, along with a slight rebound on Wall Street, offered some respite after the chaos that shook the financial system Monday when investment house Lehman Brothers declared bankruptcy and the Dow Jones industrials suffered its biggest point drop since the 2001 terrorist attacks.

Investors worried that a failure by AIG, the world's largest insurer, would set off even more financial turmoil.

A collapse of AIG would force Wall Street to untangle the complex credit derivatives markets and send the market scrambling to figure out who owes what to whom — or even who owns what.

"Regulators knew that if Lehman went down, the world wouldn't end," money manager Michael Lewitt wrote in an op-ed column yesterday in The New York Times. "But Wall Street isn't remotely prepared for the inestimable damage the financial system would suffer if AIG collapsed."

The Fed stepped in hours after it decided, in its first unanimous vote this year, to keep the closely watched federal funds rate unchanged at 2 percent. At the same time, however, the Fed noted that strains on the market have "increased significantly" and said it was ready to act if needed.

As AIG teetered, central bankers around the globe scrambled to revive credit markets. The Fed injected $70 billion into the American financial system. The European Central Bank pumped one-day financing of nearly $100 billion into the 15-nation zone. The Bank of Japan added $24 billion, and England's central bank almost $36 billion.

Cash left world markets Monday like an outgoing tide. The interest rate banks charge each other for overnight loans soared as high as 6 percent — far above the Fed's target rate of 2 percent and a sign banks didn't trust each other enough to make even 12-hour loans.

British bank Barclays PLC planned to announce by early today its intention to acquire all or part of Lehman Brothers Holdings Inc.'s investment banking and trading operations, a person close to the talks said.

Separately, Bank of America Corp., which in July bought battered Countrywide Financial Corp., began to work out how it would digest its $40 billion acquisition of Merrill Lynch after its shotgun wedding with the brokerage on Sunday.

In the wings, Goldman Sachs Group Inc., which began the year as one of five large investment banks and is now one of two, reported its worst profit drop since going public in 1999. Goldman's third-quarter profit dropped 71 percent to $810 million, while revenues plummeted 50 percent.

The only other investment bank left standing, Morgan Stanley, had better news. It reported solid quarterly profits — though down 7 percent from a year earlier — and surpassed Wall Street's expectations.

On the campaign trail, Republican presidential nominee John McCain called for a commission to study the economic crisis. Democrat Barack Obama laughed the idea off as "the oldest Washington stunt in the book."

"This isn't 9/11," Obama told a noisy crowd of more than 2,000 at the Colorado School of Mines, dismissing the idea of a need for study. "We know how we got into this mess. What we need now is leadership that gets us out. I'll provide it. John McCain won't."

McCain, campaigning in Florida, promised reforms, too, to expose and end the "reckless conduct, corruption and unbridled greed" on Wall Street that he said had caused the financial crisis.