BOSTON and PALO ALTO, Calif. — The subprime mortgage crisis has caused the number of companies sued in securities fraud class action suits to rise 43% between 2006 and 2007, according to a report from Cornerstone Research and Stanford University.

The number of cases rose from 116 to 166 over the past two years. Although litigation activity for 2007 as a whole was 14% below the ten-year historical average covering 1997–2006 of 194 companies sued per year, one hundred companies were sued in the second half 2007, a litigation rate that reversed a trend of eight consecutive quarters with below average litigation activity, the report noted.

The increase may not signal a long-term trend, according to the report. When litigation related to the subprime crisis is excluded from the calculation on the assumption that the subprime crisis is a nonrecurring event the resulting core litigation rate remains well below historical norms.