The number of class action securities fraud suits filed in federal court surged to a record high in the first half of 2017, according to a report released Tuesday, hitting the highest level in two decades as both traditional filings and merger and acquisition litigation continued to increase.

The semiannual report released by Cornerstone Research and the Stanford Law School Securities Class Action Clearinghouse found that 226 securities fraud class actions were filed in federal courts in the first six months of this year, the highest number of filings for any half year since the Clearinghouse began tracking the data in 1997.

…

The report release included a statement in which professor Joseph Grundfest, director of the Clearinghouse, said the “record-setting pace” of litigation is “causing record-setting head scratching among many analysts.”

Grundfest said part of the spike is clearly a result of the movement of M&A challenge litigation from state court to federal court after the Delaware Chancery Court took a skeptical view of such cases — federal M&A filings increased by 66 percent, to 95 federal cases, over the second half of 2016.

“But another part of the spike seems attributable to a decline in the quality of complaints filed by attorneys who have recalibrated their business strategies to pursue a portfolio of cases with more remote payoffs because the costs of building such a portfolio remains low,” Grundfest said.