Rumors about a potential merger between PepsiCo (PEP) and Mondelez (MDLZ) have been swirling for a while, but recent additions to the holdings of a couple of big name-investors is once again fueling speculation that a potential merger could be on the horizon.

Nelson Peltz's Trian Fund Management LP recently made a big investment in both companies. The fund has acquired a $1.4 billion position in Pepsi, and a $1.3 billion stake in Mondelez. As of the end of 2012, the fund had a $269 million stake in Pepsi and $494 million stake in Mondelez, so the new additions mark a significant increase in ownership of both companies.

Peltz is not the only investor taking an interest in the current situation. Activist investor Bill Ackman has also acquired a stake in Pepsi, and while his $179 investment is relatively small by his standards, it does put him in a position to have some influence over the company's future direction. Ackman is not shy when it comes to exerting his opinions on companies in which he invests, so we can expect to hear more from him in months ahead.

Pepsi has publicly said that it is not interested in any major deals, but with such big-name investors building positions it may find itself facing increased pressure to work something out with Mondelez.

Pepsi already has a formidable snack lineup through its Frito-Lay brands, but Mondelez's snack offerings would be a perfect compliment to its current lineup. Mondelez, which was spun off from Kraft (KFT) last year, is the name behind popular brands such as Chips Ahoy, Oreo, Ritz and Toblerone.

In my view, a merger between the companies makes perfect sense, but it may not be as simple as Pepsi buying Mondelez. Pepsi is currently restructuring some of its operations as it tries to improve the performance of its drinks business. Options being considered could including a potential spin off of the snacks unit. If that actually occurs, then a merger with Mondelez would make a lot more sense.

The fact that Peltz is increasing his stake in both companies is more interesting due to his history of doing so with the intention of forcing change in the past. One such move was made in 2008 when he was the force behind a group of investors that led to Cadbury Schweppes spinning off its beverage unit.

Pepsi has acknowledged recent discussion with Peltz in recent weeks to go over ideas for the company's future. It is unclear exactly what the future holds for Pepsi, but with Peltz and Ackman getting involved you can definitely expect some changes will be coming soon.

Michael Fowlkes is a financial writer who has been with the Fresh Brewed Media family since 2004. Over the course of his tenure with Fresh Brewed Media, he has worn many hats, including portfolio manager, options analyst, and writer. Michael received his undergraduate degree from Virginia Tech in Accounting and got his start in finance working as a stock trader for six years at Chase Investment Counsel in Charlottesville, Va.