Pershing Square, which bought its initial stake in Ceridian in December, has been pressuring Ceridian to spin off its Comdata credit card unit rather than seek a purchaser. Pershing Square is known for its shareholder activism—a tactic based on using shareholder power to influence or direct a company in a fashion conducive to shareholder value. Shareholder activism can involve trying to replace company management or pushing for a sale of part or all of the company.

In addition to Ceridian, New York-headquartered Pershing Square has of late battled McDonald’s and Wendy’s. Pershing Square succeeded in getting McDonald’s to buy back more than $1 billion in stock and pushing Wendy’s to spin off its Tim Horton’s doughnut chain. Pershing Square is now said to be raising $2 billion in order to buy a controlling stake in a big-name company.