One pundit tracking the company is particularly concerned about the performance of its foundational snacks business.PepsiCo (PEP -1.99%) stock was a notable decliner heading into the weekend, suffering a more than 2% drop on a day when the S&P 500 index it's a part of dipped only marginally. The storied drinks and snacks giant might have done better had it not been for news of a recommendation downgrade from a prominent researcher. From buy to holdWell before market open that day, Morgan Stanley analyst Dar ...