The United States has the largest food manufacturing sector of any market economy of the world. The number of food manufacturers declined by 52 percent between 1974 and 1977. On average, the top four firms control over half of sales in processed-foods product classes; this concentration rose by 10 percent between 1958 and 1977. Product diversification has accelerated. Total food and beverage advertising and sales promotion expenditures ranged between $9 billion and $14 billion in 1979. These elements of market organization affect foodindustry economic performance: profit margins, manufacturers' prices, and technological change. About half of the food industries exhibit significant performance problems.