Consumer Driven Health Care

Whether many employers shift may depend on rate stability, Bertolini said.

Express Scripts says its second-quarter net income more than tripled compared to last year, when costs from the pharmacy benefits manager's acquisition of competitor Medco Health Solutions dented its performance.

Aetna Inc.'s second-quarter earnings jumped 17 percent, and the health insurer raised its 2013 forecast as it reaped revenue and enrollment gains from its acquisition of fellow insurer Coventry Health Care.

Investors want to see whether Aetna Inc. can turn in a strong second-quarter performance of its own Tuesday following good results from the country's other biggest health insurers.

Aon PLC, the insurance brokerage, said Friday that its net income fell 2 percent in the second quarter as its expenses rose.

Consumers want more of a hand in making decisions about their health insurance.