Brazil's established soft-drink firms recently lost ground to multiple low-price entrants, with small-scale operations and minimal advertising. While incumbents attributed such undercutting to entrants' lower costs from non-compliance with the law, ‘generics’ counterargued that incumbents' high prices stemmed from unilateral market power rather than cost heterogeneity. By estimating a structural model, I can single-handedly explain established brands' high prices through low equilibrium price elasticities of demand. Tax evasion in the fringe, while plausible, appears to be offset by higher procurement costs or less efficient scale. More generally, a competitive informal sector can alleviate the allocative distortions in certain concentrated industries.