Health care stocks – specifically those of hospitals and insurers – are getting hammered after the Congressional Budget Office said that the GOP ObamaCare repeal plan could massively bring down the number of insured across the country.

Chances are that the ObamaCare repeal plan could see as many as 24 million insured wiped off the list and while these numbers are startling, even more surprising is that the uninsured population could jump by 15 million next year alone if the individual mandate is killed.

This effectively means that for hospital groups like Tenet Healthcare (THC) and HCA Holdings (HCA) there could a surge in number of uninsured patients who aren’t in a position to pay their bills. The reports of ObamaCare repeal plan saw Tenet share prices decline by 3.3 per cent and HCA by 1.5 per cent.

Insurers also fared poorly, and this time the losses extended beyond Medicaid-focused insurers Molina Healthcare (MOH) and Centene (CNC) to big players like Anthem (ANTM) and UnitedHealth Group (UNH). Molina sank 2.3 per cent, hitting its lowest level since October 2014, while Centene lost 2.8 per cent, Anthem 1.2 per cent and Dow component UnitedHealth 0.7 per cent.

The overall market saw more modest losses, with the Dow Jones industrial average off 0.2 per cent, the S&P 500 index 0.4 per cent and the Nasdaq composite 0.4 per cent.

The negative reaction of investors to the CBO report wasn’t a given, because several GOP senators used the occasion to criticize the American Health Care Act put together by House Speaker Paul Ryan. Yet Ryan said he was encouraged by CBO’s analysis. It’s possible that the report showing more than $300 billion in budget savings will help him win over enough conservatives to pass his bill.

Still, it’s unclear that anything resembling RyanCare can survive the Senate, where at least five moderate Republicans and a couple of conservatives have expressed opposition. It follows that anything which can survive the Senate may not survive the House. But if the Senate can pass an ObamaCare repeal bill through budget reconciliation, which is by no means certain, there will be tremendous pressure on all concerned to get a deal done.