Sonneborn served as the first president and CEO of McDonald's, from 1959 to 1967.

He devised the real estate model under which McDonald's controlled restaurant sites and leased them to franchisees, arguing that the company was fundamentally in the real estate business.

• He resigned in 1967 after clashing with Ray Kroc over expansion strategy.

• He previously served as vice president of finance at Tastee-Freez.