"While the board of directors had a difficult choice among well-qualified candidates, I'm confident that all of us will work together well with Pat to continue building on HCSC's success," McCaskey said in his memo. Health Care Service, a mutual insurance company owned by policyholders, has grown through the years, often by being the dominant insurer in its market, as it is in Illinois. It also has grown via merger and acquisition, while at the same time resisting opportunities to become investor-owned and publicly traded like other Blues plans, notably WellPoint Inc.