The number of companies targeted by shareholder activists hit an all-time high in 2018, as more investors launched campaigns, lobbied for and against deals, and increasingly cast their eyes on Europe.

This spike in activity coincided with the return of billionaire Carl Icahn to the activist scene after a sojourn in Washington as a special adviser to President Donald Trump. Icahn pushed for higher prices on several transactions, including Michael Dell's plans to return his eponymous tech giant to the public markets and Amtrust Financial Services' plans to go private. He also broke up Fujifilm Holdings Corp.'s takeover of Xerox Corp.

“Activism against M&A [mergers and acquisitions] reached an all-time high this year,” says Kai Liekefett, partner and chairman of the shareholder activism practice at law firm Sidley Austin LLP, noting that Icahn led the charge. “He's about to perfect the art of getting higher deal prices out of buyers.”