CHICAGO (AP) — Aetna is leaving the Affordable Care Act health insurance exchange in Illinois for 2017, further reducing competition.

Aetna’s announcement late Monday leaves six companies selling plans for next year to individuals and families on the Illinois “Obamacare” marketplace. Illinois Department of Insurance spokesman Michael Batkins says two insurers remain selling plans to small businesses.

The announcement follows UnitedHealthcare’s departure from the Illinois exchange. And Chicago-based Land of Lincoln Health is folding after suffering heavy losses.

Aetna will continue to sell coverage off the exchange. The company has declined to say how many Illinois customers it serves. Nationally, it covered about 838,000 people through the individual exchanges at the end of the second quarter.

Aetna has said it has been overwhelmed with higher than expected costs, particularly from expensive specialty drugs.