The number of court-approved securities class action settlements declined in 2010, sinking to the lowest number in more than 10 years, Cornerstone Research Inc. said in an annual report released Thursday.

There were 86 court-approved settlements during 2010, a 15% decline from 2009. Since 2001, the number of cases settled peaked at 119 during 2005, according to “Securities Class Action Settlements 2010 Review and Analysis.”

Cornerstone also found that the dollar value of all 2010 settlements dropped to $3.1 billion, down 17% from 2009.

The decline likely won’t continue, however, and a difficult economy may have helped reduce the number of approved settlements in 2010, Cornerstone said.