The U.K.'s Financial Services Authority has devised a new methodology that will allow it to determine the "cleanliness: of the U.K. markets by measuring stock price movements that occur before regulatory announcements. Using the methodology, Financial News reports, the FSA determined that insider trading may have occurred in 29.8% of the market announcements studied between 2000 and 2004.  
"The methodology," says FSA Managing Director Hector Sants, "is an important step forward in establishing the starting point against which the FSA's future work in tackling market abuse should be judged."