In 1957, Proctor & Gamble Company (P&G) (defendant) acquired Clorox Chemical Company (Clorox) in a merger. Prior to the merger, Clorox was the leading manufacturer of household liquid bleach. Clorox enjoyed a 48.8 percent share of national sales and possessed a near-monopoly position in several regions of the United States. In the year before the merger, Clorox spent approximately $5,400,000 to advertise and promote its product. P&G was the leading manufacturer of various cleaning products, including laundry detergent. In the year before the merger, P&G spent $127,000,000 on advertising and promotion for its products and was attempting to branch out from its existing product lines into complementary products. Due to the enormous volume of its advertising, P&G received discounts and enjoyed various advantages resulting from its ability to subsidize advertising costs for new products with profits from existing products. The Federal Trade Commission (FTC) (plaintiff) believed the merger between P&G and Clorox was unlawful under antitrust law and ordered that the merger be revoked. The court of appeals reversed, and the FTC appealed.