Payer

Four insurance giants — Aetna, Blue Cross & Blue Shield of Illinois, Humana and UnitedHealthcare — are returning to the Illinois health insurance exchange this year, according to Crain's Chicago Business.

Aetna's proposed $37 billion acquisition of Humana was approved by shareholders of both companies on Monday, according to Reuters.

Eight of the original insurance co-ops formed under the Affordable Care Act have shut down this year.

Duluth, Minn.-based Essentia Health and UCare have partnered on a new health plan for Minnesota residents. The new plan, called Essentia Care, is a Preferred Provider Organization Medicare Advantage Plan.

New York-based Oscar Health, a young insurance company, provides a mobile app for clients fully equipped with unique "click and appointments" options, according to the L.A. Times.

Blue Cross and Blue Shield of Illinois, the state's largest health insurer, and Downers Grove-based Advocate Health Care, the largest health system in Illinois, have created a new health plan.

UnitedHealth Group's revenue increased by 27 percent in the third quarter, to $41.5 billion from $32.8 billion last year, according to a MarketWatch report.

Hartford, Conn.-based Cigna is pulling its Florida plans from the federal health insurance marketplace, according to Health News Florida.

Medicare's annual open enrollment period began Oct. 15 and runs through Dec. 7. During this time, all Medicare beneficiaries can shop around and select new plan. However, many enrollees may face significantly higher premiums in 2016.

The following insurers made headlines this week. They are listed below, beginning with the most recent.