John Sonderegger’s association with Oscar Rennebohm and the chain of drug stores he built began in 1936, when he was hired as a part-time clerk. Sonderegger impressed Rennebohm with his business acumen, industry, and loyalty to such an extent that in 1940 Rennebohm hired him as a full-time employee. Sonderegger rose steadily in rank and importance and eventually was made President and Treasurer of the company in 1956. There he continued as CEO until the drug stores were sold to Walgreens in 1980.
“Sondy,” as he was known to his friends and associates, was an unusually effective leader with incredible capacity for hard work and mastery of detail and grand strategy. When Rennebohm embarked on a political career in 1947, he did so with confidence that Sonderegger could manage the drug stores. Rennebohm succeeded to the governorship in 1944 and named Sonderegger to brief terms as State Treasurer and later, Insurance Commissioner. In these capacities, Sonderegger helped reform the state’s fiscal system and saved the state several millions of dollars.
Sonderegger was a consummate public servant. When Rennebohm organized the Oscar Rennebohm Foundation in 1949, Sonderegger was named one of the first directors, and he served with distinction on the Board until his death in 1992. He also served on the Boards of Directors of First Wisconsin Trust Company, Madison Gas and Electric Company, Edgewood College, and Wisconsin Life Insurance Company. After the sale of Rennebohm’s drug stores to Walgreens in 1980, Sonderegger served as President and CEO of Wisconsin Life Insurance Company until it was merged into Central Life of Des Moines, Iowa. He then served as Chairman of the Board of Central Life Insurance until his retirement. In each organization, he was respected and admired for his diligence, shrewdness and good business judgment.