Legal departments are aggressively shifting work from the Am Law 100 and Am Law Second Hundred to less expensive law firms, a new study found, a trend that began to take root during the 2007-2008 financial crisis but was partly masked by a decadelong boom in transactional work.

With M&A activity down sharply the past two years, the extent of the shift is only now coming into full focus, according to a new legal market report by Thomson Reuters and the Center on Ethics and the Legal Profession at Georgetown Law.