Some activist investors are obsessed with multinational computer technology corporations; others are more concerned with snacks.

In 2010, Nelson Peltz, founder of Trian Fund Management LP, drove Kraft Foods to buy Cadbury, the British confectionery company, then guided the joint company to split in two. One piece became Kraft's North American groceries unit, the other an international snack business unfortunately called Mondelez, which owns Cadbury, Oreo, Wheat Thins, and other name brand snacks.

Peltz's new plan for PepsiCo, the world's largest snack-food maker, of which he's amassed a $1.3 billion stake, seems to build on that deal. If Peltz gets his way, PepsiCo would buy Mondelez in an all-stock acquisition for as much as $67.8 billion. The joint company, which would make about $70 billion in combined revenue, would then split its beverage business from its snacks business.

Why the trouble? For one, the soft drink industry is declining, while snacks are surging. "The carbonated soft drink business is not growing," Peltz said at the CNBC/Institutional Investor Delivering Alpha conference. Keeping snacks tied to soda is like "robbing Peter to pay Paul," he said.

The deal would almost assuredly cement Pepsi's dominance in the snack world, combining its Frito-Lay brands — Doritos, Ruffles, and more — with Mondelez's brands. "Analysts feel that using Mondelez' global distribution network would help Pepsi continue on its snack-food growth trajectory, because even though Frito-Lay is expanding, it's nevertheless been losing market share in North America," says Motley Fool.

But some insiders say the deal would be unwise. Mondelez, which was supposed to grow faster than Kraft's grocery unit, has "suffered from missteps," says The Wall Street Journal.

"Buying Mondelez would be risky for PepsiCo’s shareholders because of Mondelez’s underperformance and reliance on slow-growth Western European markets," says Bloomberg, citing an unnamed source.

As of now, Pepsi opposes the deal. If Peltz's plan is blocked, he says he will at least urge PepsiCo to split its beverage division from Frito-Lays.