Tyson Foods Inc. tumbled 3.3 percent for the biggest decline in the S&P 500 index. The Springdale, Ark., company, which is the largest meat processor in the United States, reported that its earnings in the second quarter were 36 cents a share. That missed the average analyst estimate by 9 cents. Tyson’s quarterly net income sank 42 percent as costs for chicken feed rose. Sales were $8.42 billion, falling short of the $8.57 billion projected.