Securities litigation filings in U.S. courts dropped 20 percent in 2012, a new study shows—largely because of a decline in the number of suits filed against Chinese companies.

A January report [PDF] from the Stanford Law School Securities Class Action Clearinghouse and Cornerstone Research finds that only 10 securities suits were filed last year against Chinese companies that listed in the United States via so-called reverse mergers. Many results of such deals—in which a Chinese company acquires and merges itself into an already listed U.S. company—have been plagued by accusations of fraudulent disclosures, triggering a wave of securities litigation beginning in 2010. Some 31 suits were filed in 2011, the peak of the trend.