D acquired the assets of Clorox Chemical Co. P claimed a violation of § 7 of the Clayton Act in that the acquisition of Clorox might substantially lessen competition or tend to create a monopoly in the production and sale of household liquid bleaches. Clorox was the leading manufacturer in the heavily concentrated household liquid bleach industry. Liquid bleach is the relevant line of commerce. Most manufacturers are limited to competition within a single region since they have but one plant (shipping costs). Clorox is the only firm selling nationally; it has 13 plants distributed throughout the Nation. Purex, Clorox's closest competitor in size, was available in less than 50% of the national market. Clorox had 48.8% of the national sales. All liquid bleach is chemically identical, meaning advertising, and sales promotion are vital. D is a large, diversified manufacturer of low-price, high-turnover household products sold through grocery, drug, and department stores. D did not produce household liquid bleach. Total domestic sales were more than $ 1.1 billion. D spent more than $80,000,000 on advertising and an additional $47,000,000 on sales promotion. P found that the acquisition might substantially lessen competition. P found that the substitution of D with its huge assets and advertising advantages for the already dominant Clorox would dissuade new entrants and discourage active competition from the firms already in the industry due to fear of retaliation by D. D appealed. The Court of Appeals said that D's finding of illegality had been based on 'treacherous conjecture,' mere possibility and suspicion. P appealed.