“We’ve been asked to solve a very big problem, which is to figure out new ways of health care,” John C. Stoddard, a senior executive for the new venture, testified.

The three employers combined are spending about $4 billion a year on the roughly one million people they cover. But employees “have a poor experience,” Mr. Stoddard said.

“They’re not getting the care they need, and the costs continue to rise,” he said. “We wouldn’t exist unless there was a need to come up with and find a new solution to the problem.”

The venture, which has no name and fewer than 20 employees, plans to tackle several areas, including how benefits are provided through traditional health insurance plans, Mr. Stoddard said. High deductibles, which force employees to pay for significant amounts of their care before their insurance kicks in, are a hardship for “fulfillment-center workers and call-center workers,” he said.

The companies also want to see if they can lower the cost of drugs for chronic conditions. In his testimony, Mr. Stoddard insisted that the new venture had no plans to enter the pharmacy business but wanted to better understand the process and the actual cost of drugs.

“That doesn’t make us a competitor,” he said. “That makes us a very informed customer.”

The employers also want to make it easier for workers to see a doctor, Mr. Stoddard testified. Because Optum also operates a large network of primary-care doctors, the venture might want to work with Optum to provide employees with easier access to physicians.

“That’s why this is so crazy to me: that they think of us as competitors, when I see us as potential partners,” Mr. Stoddard said.