This means Aubrey borrowed a whole bunch of money using his stock as collateral probably to buy boats and ranches and more CHK stock, so when the stock price plummeted by 70% or more like it did, the bankers just sell you out to pay off your loans.

FORBES: Aubrey's Gone Let's Sing A Song

So the Federal Reserve agreed to lend it tens of billions of dollars, taking AIG stock as collateral.

NPR: U.S. Boosts AIG Bailout Package

Big banks and asset managers will have to do a better job of keeping track of margin requirements and the available stock of eligible collateral they have.

ECONOMIST: Collateral management

Many senators voted for the bill because of last-minute additions forcing airlines not to shut down business in small communities and a provision to allow the government to receive airline stock options as collateral for the loan guarantees.

CNN: Congress approves $15 billion airline bailout

The alleged method: borrowing shares of restricted stock in several small companies to use as collateral for loans without telling the banks the shares were borrowed.

FORBES: Fraud per capita

It did this by classifying such subsidiary sovereign debt as the highest quality collateral - which means that banks wanted an ample stock of it, just in case they needed assets to swap for central bank loans.

BBC: The eurozone's borrowing costs may stay lethally high

As Microsoft shares tumbled in the tech crash, Lewis had to sell stock to meet Merrill's margin calls, demands for more loan collateral.

FORBES: Out of Options

Lay put up a chunk of his Enron stock and a smaller percentage of his more liquid assets (cash and real estate, for example) as collateral for the loans.

FORBES: Ken Lay's Self-Inflicted Wounds