You'd think I'd be able understand this but by the time I got midway through the article, my head started hurting.

Wall Street Says -2 + -2 = 4 as Liabilities Get New Bond Math
By Bradley Keoun

Merrill Lynch & Co., Citigroup Inc. and four other U.S. financial companies have used an accounting rule adopted last year to book almost $12 billion of revenue after a decline in prices of their own bonds.

The new math, while legal, defies common sense.

"They can post substantial gains as a result of a decline in their own creditworthiness," said James Cataldo, a former director of treasury risk management for the Federal Home Loan Bank of Boston and now an assistant professor of accounting at Suffolk University in Boston. "It's completely legitimate, but it doesn't make sense by any way we currently have of thinking of net income."