US moves to block massive health insurer deals led by Anthem, Aetna

New York

US antitrust officials moved to block an unprecedented consolidation of the national health insurance market, filing a lawsuit against Anthem Inc's proposed purchase of Cigna Corp and Aetna Inc's planned acquisition of Humana Inc.

The US Department of Justice said that the two multibillion-dollar mergers would reduce competition, raise prices for consumers and stifle innovation if the number of large, national insurers were to fall from five to three.

It was the latest example of the Obama administration challenging massive combinations in major industries, from oilfield services to telecommunications.

"We will not hesitate to intervene. We will not shy away from complex cases," US Attorney-General Loretta Lynch told a n…