The report, “Elephants in the Room Part I: The Big Four's Expansion in the Legal Services Market,” by ALM Intelligence, says that the Big Four's formidable brand strength, client base and ability to offer multidisciplinary services has helped them take market share from traditional law firms. (The American Lawyer analyzed the Big Four's legal services ambitions in a 2014 feature story.)

Deloitte, EY, KPMG and PricewaterhouseCoopers have invested heavily in their legal services arms in recent years—particularly in Europe—and now collectively employ about 8,500 attorneys globally.