2006 price change: -34.1%

After partying in 2005 thanks to gains it made against bigger semiconductor rival Intel, AMD has been nursing a hangover this year. The company has continued to win market share from its bitter competitor, but their fierce battle is taking a toll on both chipmakers. (Intel is the 10th worst performing tech stock in the S&P 500 this year.)

2007 outlook: As businesses slowly upgrade their networks to Microsoft's Vista operating system, the chip sector could benefit. But AMD will keep facing tough competition from Intel, which is in the midst of a broad restructuring. One positive note: the company expects to start shipping a new lineup of “quad core” processors - chips with four brains on them - in the middle of next year.