By Deena Beasley

Health insurer Cigna is in merger talks with Humana, a source familiar with the matter said on Wednesday, potentially marking the latest in a long string of deals aimed at consolidation of the industry.

The U.S. Department of Justice, citing the prospect of higher prices, in 2016 successfully sued to stop two proposed mega mergers: Anthem's - now Elevance Health - planned $54 billion purchase of Cigna and Aetna's proposed $34 billion acquisition of Humana.

The companies said those proposed deals were triggered by the Affordable Care Act, which was fully implemented in 2014. Here is what has happened in deals involving health insurers since the law went into effect:

2015: UnitedHealth acquired pharmacy benefit manager Catamaran for $12.8 billion, merging it into its existing OptumRx drug benefit unit.

2015: Pharmacy chain CVS Health acquired Omnicare, a provider of pharmacy services to long-term care facilities for more than $12 billion.

2015: CVS Health acquired Target's 1,600-plus pharmacies and retail medical clinics inside Target stores for nearly $2 billion.

2017: CVS Health announced plans to acquire health insurer Aetna for $69 billion in the largest-ever healthcare merger.

The companies said they would save administrative and patient care costs, in part by steering Aetna customers to walk-in clinics in CVS stores for less expensive medical services.

October 2017: Anthem announced that it would not renew its pharmacy benefit management relationship with Express Scripts and subsequently entered into a new contract with CVS Health.

March 2018: Health insurer Cigna announced plans to acquire Express Scripts for $52 billion.

November 2018: CVS Health completes its $69 billion acquisition of Aetna.

June 2019: UnitedHealth acquires the primary and urgent care services of DaVita for $4.3 billion.

March 2022: UnitedHealth announced it would acquire LHC Group for $5.4 billion. The deal closed in February 2023.

September 2022: CVS Health announced that it reached an agreement to buy at-home health company Signify Health for roughly $8 billion. The deal closed in March 2023.

February 2023: CVS Health entered into a definitive agreement to acquire primary care center operator Oak Street Health for around $10 billion. The deal closed in May 2023.

(Reporting by Deena Beasley; Additional reporting by Diane Bartz in Washington; Editing by Christopher Cushing)