Anthem and Cigna have accused each other of violating their merger agreement, the Justice Department said in a court filing.

Both Anthem and Cigna shares rose when a DOJ lawyer told the judge in the antitrust case that the feds would hear settlement offers. But that's no guarantee an agreement could be reached.

The Justice Department filed an antitrust lawsuit to stop the Anthem-Cigna and Aetna-Humana deals.

A suit may be filed soon to block Anthem's takeover of Cigna and Aetna's deal to buy Humana, sources say.

Aetna is preparing to meet with top U.S. Justice Department officials on Friday as it seeks to win antitrust approval for its Humana deal.

The Justice Department has told Anthem that the health insurers planned takeover of Cigna threatens competition and probably cant be fixed by selling parts of their businesses, according to a person familiar with the matter.

What if the Anthem-Cigna deal doesn't go through? Small insurers might become targets for acquisition.

Market review by U.S. antitrust officials could prevent the health insurer deals. Here's why.