Securities plaintiffs lawyers are a resourceful breed, and a new report suggests that their hardiness is being put to the test. Federal securities class action filings dropped by 20 percent in 2012, according to a report by Cornerstone Research and Stanford Law School. Experts said the downturn wasn’t surprising, given the steep obstacles thrown up by the courts, and the near-death of two litigation trends: cases related to the 2008 credit crisis, and cases against Chinese companies that obtained U.S.-listings through a controversial practice known as a reverse merger.

The Cornerstone report showed that shareholders brought 152 securities class actions in federal court in 2012, compared to 188 in 2011 and 176 in 2010. The 2012 tally is the lowest since 2006, when shareholders brought 120 cases. According to the report, the average number of filings per year between 1997 and 2011 was 193.