Obamacare insurer Anthem (ANTM) - Get Report is said to be exiting "a high percentage" of the insurance regions where it is currently selling individual health plans. Should this happen millions of Obamacare customers and potential customers will be left with fewer choices in 2018, CNBC reports.

The analysis comes from a Jefferies report issued on Thursday and follows Anthem CEO Joseph Swedish's warning from two months ago that the company would be deciding "whether or not we surgically extract ourselves from certain rating regions, or even on a larger scale, depending on the stability of the marketplace."

Earlier in March a report by Axios said that an Anthem exit would cause "the most disruption nationwide," leaving 255,000 people across Kentucky, Colorado, Missouri, and Ohio with no Obamacare next year, CNBC noted. About 560,000 people in eight states would have only one insurer.