Obamacare stocks are getting slammed as the future of the law is in question

Health services providers that have benefitted from the Affordable Care Act (ACA) are getting rocked in pre-market trading after the presumed election of Donald Trump as the next president of the the US.

The ACA has benefitted health care services and hospital companies as more than 20 million American have gained health insurance.

The thinking is that higher use of health care facilities and fewer losses from uninsured patients would be beneficial to these firms.

Now, with Trump elected and a Republican Congress, recent calls for the repeal of the ACA, better known as Obamacare, are more likely and could lead to the loss of these financial benefits.

Here's a quick rundown of the hardest hit stocks:

• Hospital Corporation of America, which manages 168 hospitals and 116 surgery centers, is down -15%.
• Universal Health Services, manages hospitals and clinics, is down -11.5%.
• Lifepoint Health, a rural-focused healthcare services provider, is down -13%.
• Tenet Healthcare, owner of 470 outpatient facilites and other healthcare service proviers, is down -27.5%

Large health insurers such as Aetna, UnitedHealthcare, and Humana that have recently rolled back a significant amount of their Obamacare business are relatively unchanged in pre-market trading.