CVS Health Corp. completed its nearly $70 billion acquisition of Aetna Inc., forging a new industry giant and starting the clock ticking on ambitious goals of curbing health care costs and improving consumers’ experience. The combined company faces significant challenges in bringing together its diverse set of health assets, including CVS’s sprawling network of pharmacies, a pharmacy-benefit manager, and Aetna’s employer insurance, Medicare, and Medicaid managed care businesses. (Anna Wilde Mathews and Aisha Al-Muslim, Wall Street Journal)