Securities defense lawyers at big firms have noticed an uptick in shareholder lawsuits over mergers and acquisitions, even those worth under $100 million, a reflection of both increased deal activity and eroded share values that have lowered sale prices.

“There’s clearly been more cases filed over the last three months than in the comparable period the year before, both here in California and in Delaware,” said Kevin Muck, head of securities litigation at Fenwick & West.