Insurers and drug benefit managers, who mediate between employers and pharmaceutical companies, also monitor employers.

"You have this influx of new threats," said Paul Keckley, health policy analyst.

Two major health insurance companies, Aetna and Cigna, have recently merged with pharmacy benefit managers. Anthem said Wednesday that he was quickly preparing to set up an internal operation, to end his relationship with Express Scripts, responsible for pharmaceutical benefits, earlier than expected after the acquisition of Cigna.

Until recently, large employers were generally not considered competitors of insurers and drug benefit managers who process their employees' claims, although the announcement of the creation of ABJ expressed frustration with the US health care system.

The new Big Three company "has no name yet, let alone revenue," said David Johnson, managing director of 4sight Health, a consulting firm. "I'm struck by the fact that they should try to woo ABJ rather than sticking them in the eyes."

The real threat to Optum might well be Amazon, which has already done forays into the pharmacy sector and is willing to sacrifice profits as he gains market share. Optum is vulnerable because its clients – particularly employers – have little information about its operations, ranging from health data services to pharmaceutical benefits, said Michael Turpin, former UnitedHealth executive vice president executive of USI, an insurance brokerage company.

"It's really the most opaque of all the black boxes in health care," said Turpin. He added: "Amazon is lying in the grass and will one day come up and do something disruptive around the pharmacy."

[[[[Like the Science Times page on Facebook. | Sign up for the Science Times Bulletin.]

In its depots, Optum assumes the worst, claiming that the new company will eventually decide to offer services to the rest of the world. He describes Mr. Smith as asking "the court to ignore the reality and think that ABC is just a nonprofit start-up with the sole purpose of improving health outcomes." employees of its founding companies ".