Last week saw two publicly-traded companies lose their AAA credit ratings. That might not sound like a lot ... until you realize that there were only seven to start with!

First, Standard & Poor's downgraded General Electric on March 12. Then, later the same day, Fitch took Berkshire Hathaway down a notch, too.

That leaves just five companies with AAA ratings: Automatic Data Processing, Exxon Mobil, Johnson & Johnson, Microsoft, and Pfizer.