The drop in health insurance stocks after the landmark partnership announcement by Amazon, Berkshire Hathaway and J.P. Morgan Chase is a buying opportunity, according to one Wall Street firm.

The three companies announced a partnership on Tuesday to devise ways to cut health-care costs and improve services for their 1.1 million employees. The firms will launch an independent outfit initially targeting technology solutions, with the intention to be an umbrella firm that would be "free from profit-making incentives.

"While we do not want to discount the clout that these entities potentially bring to the table, it is entirely too early to cede victory to the yet unnamed venture," Cantor Fitzgerald analyst Steven Halper wrote in a client note entitled "Amazon/Berkshire/JPM Joining Forces; More Bark than Bite at this Point."

UnitedHealth Group dropped 3 percent by midday. Anthem was off by 5 percent, Aetna fell by 3 percent, Centene was 1.5 percent lower.

The analyst expressed doubt on the venture due to the lack of industry management experience of the executives put in charge of the new organization such as Berkshire's Todd Combs, a former hedge fund manager.

"This is not a new concept within the healthcare benefits world. These companies are probably self insured and already use a wide range of solutions to administer benefit solutions to their employees," Halper wrote in an email to CNBC. "We do not believe this represents a new competitive threat to the managed care companies at this juncture."

The analyst reiterated his overweight ratings for Anthem, United Health and Centene.