The fact that Quinn Emanuel Urquhart & Sullivan’s biggest financial crisis case for American International Group Inc. ended a day before news broke that General Motors Co. hired the firm to review its litigation process is a coincidence. But the two developments reflect the firm’s strategy: As some of its biggest cases wind down, it’s branching out and landing new assignments, ranging from pursuing antitrust class actions to defending the upstart ride-sharing company Uber Inc. in a batch of lawsuits.

Quinn Emanuel has benefited greatly in recent years from representing Samsung Electronics Co. and Motorola Mobility Inc. in smartphone patent litigation. And since the financial crisis, the litigation-only firm has also carved out a niche representing mortgage-backed securities investors like AIG, MBIA Inc. and the Federal Housing Finance Agency. It’s lucrative work that bigger, older firms couldn’t handle because of their ties to Wall Street banks that sold these securities. Defending Samsung and suing Wall Street led to record revenue in 2012 and 2013.