Anyone wondering how badly the U.S. economy is stumbling should take a look at what's happening with corporate credit ratings.

In boom times, ratings companies such as Moody's Investors Service, Standard & Poor's Corp. and Fitch Ratings issue lots of upgrades as corporate finances strengthen. When trouble hits, downgrades become the norm.

Over the past few years, the zigzags of this up/down ratio have closely matched changing economic conditions. In the first quarter of 2007, according to data compiled by Bloomberg, the up/down ratio for Moody's U.S. corporate ratings hit a peak of 2.16. The ratio plummeted to 0.09 in the first quarter of 2009, amid a torrent of downgrades. (A ratio below 1 means downgrades outnumber upgrades.) Earlier this year, the ratio provided relatively neutral readings close to 1.00.

So how are we doing now?

Not well. Since July 1, Moody's has issued just 60 corporate upgrades versus 134 downgrades. That amounts to an up/down ratio of just 0.45. Recently downgraded companies include Frontier Oil Corp., Sears Roebuck & Co., Media General Inc. and Jack in the Box Inc.

August is looking even worse. The Moody's up/down ratio has tumbled to 0.17, the lowest level since the second quarter of 2009. The numbers from S&P are hardly any better. The up/down ratio on its ratings for August is 0.22.

Credit ratings have been in the headlines lately because of S&P's decision to cut the U.S.'s long-term debt rating one level to AA+ from AAA. Corporate ratings, which are evaluated by different teams inside the ratings companies, haven't attracted much notice. Perhaps they should.

(George Anders is a member of the Bloomberg View editorial board.)