If S&P's Downgrade Was So Important to Financial Markets, Why Did Bond Prices Soar?

It's pretty bad when our nation's leading newspaper can't tell which way is up. The NYT told readers today that:

"members of Congress are investigating why S.& P. removed the nation's AAA rating, which is highly important to financial markets."

If the triple A rating is so important to financial markets then why did bond prices soar in the first trading day after the downgrade. The downgrade should have meant U.S. government debt is viewed as more risky. This means that government bonds...