In a regulatory filing, Trian said it began building stakes in both companies in late 2012, buying about $270 million worth of stock in PepsiCo and a $500 million stake in Mondelez. Yet sources tell CNBC that over the last several months, Peltz has added to those stakes materially—Trian now holds about $1.4 billion in Pepsi and $1.3 billion in Mondelez, a spinoff of Kraft Foods.
Analysts have speculated that Peltz's interest in the two companies stems from trying to effect a merger between Pepsi and Mondelez. Some have floated the idea that Pepsi might spin off its Frito-Lay division and merge it with Mondelez, whose CEO Irene Rosenfeld used to run Frito-Lay.
In a statement, Pepsi said that management had been in talks with Trian in order to "discuss and consider their ideas and initiatives as part of our ongoing evaluation of all opportunities to drive long-term growth and shareholder value." The company added that it looked "forward to continuing constructive discussions with them."