It's the largest bankruptcy filing in U.S. history.

Lehman Brothers files for chapter eleven bankruptcy protection.

The financial giant says it will slowly wind down operations after being in business for one hundred fifty eight years.

Many of Lehman employees spent the day clearing out desks...unsure of the next chapter in their lives while Lehman heads for chapter eleven.

The company decided to file for bankruptcy after being unable to find a buyer.

A potential contender-- Bank of America --instead bought out Merrill Lynch.

And that was just one of the mega-deals sweeping the street.

New York Governor David Paterson is providing state money to AIG...another troubled financial company.

Paterson says it’s imperative to keep the big banks going.

"The ramifications of the plight of many of these companies will probably not be fully appreciated for days months or maybe even years,” said New York Governor, David Paterson.

Treasury Secretary Henry Paulson says the American people can remain confident in the nation's financial system.

But Paulson says regulatory changes are needed to deal with the new economy.

"In the immediate and longer term, clearly we're going to need major regulatory changes, and I’ve spoken a lot about that, and we could use additional authorities to deal with non-bank financial institutions,” said Treasury Secretary, Henry Paulson.

To give you an idea of the magnitude of this bankruptcy – $639 billion...that's more than Enron and WorldCom combined.

And with thousands expected to lose their jobs right here in New York City.

The Mayor Michael Bloomberg says New York can handle it, but it won't be easy.