Moody's has put Nasdaq on ratings watch for a possible downgrade.

The rating agency placed Block's $1.15 billion under review yesterday for possible downgrade.

It has also put a number of large European banks on review for a possible downgrade.

S&P said further banks would be put on notice for possible downgrade.

Last week, major rating services placed airport bonds on review for possible downgrades.

The ratings are still subject to a possible downgrade, Moody's said this week.

Ratings agencies are watching Japan with an eye toward a possible downgrade.

Fitch says 14 Spanish local, regional governments face possible downgrade.

For more on the possible downgrade, take a look at:

Standard & Poor's, the rating agency, also placed the center on a watch list for possible further downgrade.