Insurance companies are worried plans to repeal and replace the Affordable Care Act (ACA) may create the very “death spiral” opponents of the law have claimed is already happening.

President-elect Donald Trump has said he’d like to keep two parts of the ACA: the ban on insurers denying coverage based on preexisting conditions and keeping kids on their parents’ plans until they reach the age of 26. According to The Hill, insurers want to warn the Trump administration that without requirements for buy health insurance, only sick people will purchase coverage, sending premiums skyrocketing and causing the market to collapse—a “death spiral.”

“There’s a huge amount of uncertainty that I think freaks them out a little bit,” one insurance lobbyist said.

A cautionary tale can be found in New York, where before the ACA existed, a pre-existing condition ban with no individual mandate was put into place. The plan failed.

“It was a market in a death spiral, and by that I mean the premiums were exorbitantly expensive,” Sabrina Corlette, a health policy professor at Georgetown University. “Very few people were able to enroll.”

For more on how even a delayed repeal of the ACA worries insurers, click on the link below: