Here's a good story from AP:

The government's "stress tests" of 19 large banks take a harsher view of loans than of other troubled assets, according to a Federal Reserve document obtained by the Associated Press. That approach favors a few Wall Street banks while potentially threatening major regional players. Regulators will use the tests to determine which banks are healthy, which need more capital and which might fail if the recession worsened.

The regulators' focus could spell trouble for big regional banks undergoing the tests. Their portfolios have more individual loans and fewer of the big pools of securitized loans that Wall Street giants specialize in.

Some analysts said regulators are favoring the largest banks because if even one failed that would pose a severe economic risk. Banks that deal in securities are more interconnected to other corners of the global financial system.