Breaching Myriad's walls

Myriad Genetics Inc. (NASDAQ:MYGN) jumped more than 10% in intraday trading Thursday as the company claimed victory on a U.S. Supreme Court ruling allowing cDNA patents. But the shares ended the day down 6% and tumbled further Friday after several companies announced plans to offer competing breast cancer tests priced as low as one-third of Myriad's