Amazon has disrupted fashion, books, furniture, food, cloud-based storage services, and much else besides. Now, it’s coming for one of the biggest, most complex industries in the US: healthcare.

Today (Jan. 30), Amazon, Berkshire Hathaway, and JPMorgan announced a vague but market-moving plan to launch an independent company that will offer healthcare services to the companies’ employees at a lower cost. The venture, which will be managed by executives from the firms, will be run more like a non-profit, than a for-profit entity.

The market value of 10 large, listed dropped by a combined $30 billion in the first two hours of trading. At the time of writing, insurer MetLife was the hardest hit, down nearly 9% for the day.

1 Aetna, Anthem, Centene, Cigna, CVS, Express Scripts, Humana, MetLife, UnitedHealth, Walgreens Boots

“The healthcare system is complex, and we enter into this challenge open-eyed about the degree of difficulty,” said Amazon’s Jeff Bezos in a statement. “Hard as it might be, reducing healthcare’s burden on the economy while improving outcomes for employees and their families would be worth the effort. Success is going to require talented experts, a beginner’s mind, and a long-term orientation.”

Warren Buffett, the CEO of Berkshire Hathaway, likened America’s mushrooming healthcare costs to “a hungry tapeworm on the American economy.”

How the venture will provide less pricy healthcare to the 1.2 million employees of the participating companies isn’t yet clear. The new company will leverage “technology solutions” that provide “simplified, high-quality and transparent healthcare at a reasonable cost.” Not much else, including the name of the company, is known.

Health insurance provider Aetna, which posted expectations-beating quarterly earnings (pdf) just hours before the Amazon/JPMorgan/Berkshire announcement, saw its share price sink by more than 2%. Many other large healthcare companies are reporting earnings in the coming days, and it’s clear what the most pointed questions from analysts on conference calls will be about.