The combination of Aetna and Humana:
Builds on each company’s respective efforts to provide innovative, technology-driven products, services and solutions to build healthier populations, promote higher quality health care at lower cost, and offer greater transparency and convenience for consumers.
Increases Aetna’s Medicare Advantage membership to 4.4 million and improves Aetna’s ability to serve members and their providers with cutting-edge technology and best practices.
Brings together two companies with leading percentages of membership in Medicare plans rated four stars or higher.
Creates a leading health care services and pharmacy benefit franchise, serving members who use over 600 million prescriptions annually.
Strengthens care management capabilities by taking the best-of-breed provider solutions, including robust offerings of patient-centered provider services, clinical intelligence, value-based reimbursement models, data integration and analytics solutions from both companies.
Brings together two companies with longstanding commitments to promoting wellness, health, and access to high-quality health care for everyone, while supporting the communities in which they serve.

Impressive. The combined company would be the second largest health insurer after United Healthcare. The Wall Street Journal reports that

Both chief executives said they are confident the transaction will be approved, citing complimentary, rather than overlapping strengths—Aetna in commercial selling, and Humana in Medicare. Antitrust reviews are “never totally predictable, but we believe it’s very manageable,” Aetna CEO Mark Bertolini said.  

The Journal further explains that

A takeover approach for Humana earlier this year thrust the biggest health-insurance companies into a five-way merger frenzy. Cigna Corp. and Aetna were vying to buy Humana, while fielding takeover approaches of their own. Cigna and Anthem Inc. have rekindled talks after Cigna earlier rejected a public takeover bid of $184 a share from Anthem, its larger rival, and UnitedHealth Group Inc. earlier approached Aetna.
Meantime, Medicaid-focused Centene Corp. said Thursday that it agreed to buy Health Net Inc., in a deal worth about $6.3 billion.  The consolidation momentum in the health-insurance industry is being fed by a desire to diversify and cut costs, amid a landscape changed by the Affordable Care Act. 

Mr. Toad’s wild ride.