In 1983 Karl became Chairman of the Board and Chief Executive Officer of the Circle K Corporation and resigned those positions in 1990. During that time, he built Circle K into the second largest convenience store operation and the largest publicly owned convenience store chain in the United States. He built the company from 1,221 stores in 11 western states to 4,641 stores in 32 states and an additional 1,386 licensed or joint venture stores in 13 foreign countries.