Shares Aramark  (ARMK) - Get Report  hit a new 52-week high Monday after the food-services giant announced an agreement with activist investor Mantle Ridge that calls for a new CEO and changes to the board.

Veteran executive John Zillmer has been appointed CEO and will join Aramark's board as one of several new directors. He replaces former CEO Eric Foss, who departed in August.

"John Zillmer is an outstanding leader with a proven record of accelerating business performance and fostering a strong corporate culture," Aramark Chairman Stephen Sadove said in a statement, which noted that Zillmer had previously worked for the company for 18 years.

The news sent ARMK rising as much as 3.4% Monday to $44.16, a new 52-week high. Shares pulled back slightly later in the session, but were still up 2.4% at $43.72 shortly before noon ET.

Mantle Ridge has built up a 20% stake in Aramark, a global leader in food, facilities management and uniforms. That makes the company ARMK's largest shareholder.

As part of Monday's moves, Mantle Ridge CEO and Founder Paul Hilal will also join Aramark's board as vice chairman. Other new board members include:

  • Reynolds American CEO Susan Cameron
  • Art Winkleblack, former chief financial officer of H.J. Heinz Co.