U.S. antitrust regulators will announce on Thursday plans to file lawsuits to block two separate health insurance mergers, Anthem Inc's (ANTM.N) purchase of Cigna Corp (CI.N) and Aetna Inc's (AET.N) acquisition of Humana Inc (HUM.N), according to a source familiar with the matter.

 

The U.S. Department of Justice has been reviewing the deals for the past year and has been concerned that the combinations would reduce competition. There are currently five national health insurers, and the deals would reduce that number to three.

 

The Justice Department said in a press release that it would hold an 11 a.m. news conference to announce significant antitrust news.

 

Antitrust regulators had been expected to file lawsuits aimed at blocking both deals by the end of next week, Reuters reported earlier this week.

 

Shares of Humana fell 1.8 percent to $155.50 and Cigna rose 0.1 percent to $133.25. Aetna and Anthem shares were both up slightly in morning trading.