The average shareholder class action settlement was $18.2 million last year, down 75 percent from 2016 and well below the $57.7 million average over the past two decades, according to an annual report by Cornerstone Research.

The report, released Wednesday, said that the total of all settlements was $1.5 billion, less than a quarter of total settlement values in 2016 and the second-lowest level in the past decade.