How will things change once Cigna takes over Express Scripts, one of the industry's largest pharmacy benefits managers?

Adding more direct-to-consumer health services could be crucial for the success of CVS's $68 billion merger with Aetna, which the companies have touted as a way to control medical costs.

UnitedHealth is betting that controlling many doctors can provide patients better care at a lower cost.

Including changes based on how sick or healthy people are, the total increase in payments to insurers is estimated to be about 6.5 percent, on average,

A deal or joint venture between Humana and Walmart might help defend against competitive threats in both the retail and health care industries.

Walmart and Humana have explored a wide range of options including a merger, though an outright combination isn't likely at this point, according to one source.

The discounts, which can amount to more than half a drug's list price, will be passed on at the pharmacy counter for many people starting next year.

"We are disappointed that we have not achieved more at a faster pace," Marcela Hawn, a spokeswoman for the company, said in an email.