Circle K operator Alimentation Couche-Tard is likely to face a tough U.S. antitrust review if it moves forward with its $47.2 billion bid to buy 7-Eleven owner Seven & I Holdings.

The companies directly compete in thousands of locations across the United States, with more than 45% of Circle Ks within two miles of a 7-Eleven or related store, according to data compiled by Bloomberg.

Jennifer Rie, Bloomberg Industries antitrust analyst, said that the "chances are very high” the U.S. Federal Trade Commission may find the concentration levels problematic.