Mondelez CEO Irene Rosenfeld has the ill-fated distinction of being one of the business world’s foremost experts when it comes to dealing with activist investors. Activists circled Kraft in 2011 as she made the decision to break the company into two. Now as the head of the resulting $34 billion snack business whose brands include Oreo, Ritz, and Trident, Rosenfeld is feeling the pressure again. Hedge fund manager Bill Ackman announced in August that he had taken about a 7.5% stake in Mondelez