Harken Health — billed as an "innovative" health insurer and started by America's biggest insurance company to appeal to Obamacare customers — will exit the only two government-run exchange markets where it was selling coverage after reportedly booking losses of about $70 million in the first half of this year.

Harken in August said it was abandoning plans to sell Obamacare exchange coverage in Miami and Fort Lauderdale, Florida, next year.

But its departure in 2017 from the Obamacare exchanges that serve those cities represents another setback for advocates of the Affordable Care Act and their efforts to offer individual health plan customers a broad range of affordable coverage options.

The UnitedHealth Group unit — which offers unlimited primary care visits at no out-of-pocket cost to customers who use Harken Health clinics — continue selling plans outside of Obamacare exchanges in the individual and employer markets of both Chicago and Atlanta next year.

And Harken's parent, UnitedHealth, earlier this year said it would itself exit most Obamacare exchanges, including the federal marketplace that services Illinois, in 2017.

Harken, in statement to CNBC, said, "Harken Health remains committed to our innovative model of insurance paired with access to relationship-based care and we look forward to continuing to offer plans to individuals and employers who purchase coverage outside of the exchange."

The Chicago Tribune noted that because of Harken's exit from the exchange, residents of Cook County, which includes Chicago, will have just three insurers to choose from if they want to buy coverage on HealthCare.gov, the federal Obamacare exchange that serves Illinois and 37 other states.

HealthCare.gov and state-run Obamacare exchanges are the only places that low- and moderate-income customers receive subsidies, in the form of federal tax credits, to lower the cost of their monthly premiums.

The subsidies, whose amounts are linked to income levels and the premium charges, can significantly reduce the cost of coverage.

People who buy Harken Health plans, or any other individual plans, outside of the exchanges must pay the full premium.