Mars announced the deal, which valued Kellanova at $35.9 billion, earlier Wednesday. Kellanova formed when Kellogg Company split into two companies in September 2023.
Kellogg Company and Mars accounted for 49% of U.S. snack and cereal bar sales in 2022, according to FWW, which pointed to research showing that "growing market concentration leads to fewer consumer choices and rising food prices."
Starbuck said the current trend of food monopolies must be reversed.
"American grocery shoppers are suffering from high prices and fewer choices on the shelves—Mars' Kellanova acquisition would only make it worse," she said. "While processed food giants stand to ramp up profits from snack market domination, the American consumer will lose out with higher costs and fewer healthy options. A shrinking number of ever-larger corporations control a growing share of the food we buy, putting decisions about our health and finances in the hands of corporate kingpins."
Despite Starbuck's concerns, the deal has a good chance of gaining approval by federal antitrust regulators, Reutersreported last week.
Kellanova CEO Steve Cahillane told CNBC that he doesn't foresee any antitrust issues, though Daniel Hanley, a legal analyst at Open Markets Institute, expressed skepticism about the merger's legality in social media posts.
Another food-related merger under antitrust scrutiny is Kroger's $24.6 billion proposed acquisition of Albertsons, which the Federal Trade Commission, led by Chair Lina Khan, has sued to block.
