Try and figure out the mind of the market, it's always a mystery. Shares in American Express rose 9% after it beat analysts estimates for third quarter earnings. That's despite a 23% drop in third-quarter income from continuing operations. More from Bloomberg.

But that hasn't stopped Moody's from cutting the Amex credit rating because of deteriorating US economic conditions. As Reuters reports, the credit card issuer is heavily exposed to consumers hit hard by declining housing prices.

Is Amex a good buy? It's worth taking a look at the numbers buried in its accounts. Consolidated revenues were up only 3%. But the big red flag lies in the consolidated provisions for losses.

"Consolidated provisions for losses increased 51% versus last year...Provisions rose primarily due to the difficult credit environment, which led to increased write-off and delinquency rates versus last year and increased merchant-related reserves."

There it is in black and white. Pity investors don't look that far.