Activist investor Nelson Peltz is shaking things up in the snack-food world. He recently expressed strong feelings about a proposed PepsiCo (NASDAQ:PEP) and Mondelez International (NASDAQ:MDLZ) merger. So far, PepsiCo management hasn't nibbled on the idea. Yet, there are two main reasons Peltz's proposal has merit.

1. Synergies and scale
A merger of PepsiCo's salty snacks with Mondelez's sweet treats would create a company with nearly $70 billion in annual revenue and a super-strong franchise of almost a dozen-and-a-half iconic billion-dollar brands like Lay's, Doritos, Oreo, and Cadbury. Peltz laid out in his megadeal the synergies and economies of scale he feels could be gained by putting PepsiCo's chips and Mondelez's cookies on the same trucks to the same markets worldwide.

By leveraging Mondelez's global distribution network, the activist investor feels PepsiCo can turnaround its declining snack-food growth trajectory. The overall snack category has been growing, but organic growth for PepsiCo's Frito-Lay North American business has decelerated. In fact, it's slowed from 6% annually between 2002 and 2009, to 3% between 2009 and 2012. Peltz feels the main reason for this decline is that the company is being weighed down by the beverage business.

2. Shedding an underperforming business
As U.S. cola sales have decayed, and market share has been lost to Coca-Cola, Peltz feels PepsiCo should divest its slower-growing beverage business, allowing it to concentrate on its more-profitable snacks. Beverages bring in nearly half of PepsiCo's annual revenues, yet they're a drag on the company's operating profit. The activist investor believes the merger could yield an implied value of $175 per share for PepsiCo, and $72 per share for Mondelez, by the end of 2015. 

Peltz feels PepsiCo could achieve substantial increases in shareholder value worth at least $33 billion by cleaving the beverage business, and merging the remaining snack business with Mondelez, whose stock has languished since splitting from Kraft Foods Group (UNKNOWN:KRFT.DL) last year. The activist investor points to several examples of other similar acquisitions and divestitures to support his idea, including PepsiCo's spinoff of Yum! Brands (NYSE: YUM).

Peltz has a history of shaking things up with the industry. The investor played a key role in Cadbury splitting its beverage and candy businesses, and then getting what was Kraft Foods to buy Cadbury. Peltz then helped Kraft spin off its slow-growing North American grocery business, now know as Kraft Foods Group, from its global snack-food business, which was renamed Mondelez.

Foolish final thoughts
Recent investor campaigns against major companies -- like Bill Ackman's successful ousting of former Procter & Gamble CEO Bob McDonald -- have garnered attention, underscoring that the business community is searching for ways to optimize shareholder value. PepsiCo has made it clear that it's not embracing Peltz's proposal. But his prodding may influence some type of future action from PepsiCo and Mondelez.