Cigna Group and Humana Inc. are in talks to merge in a cash and stock deal that would create another dominant force in the health-insurance industry, according to the Wall Street Journal.

An agreement to combine the giant insurers could be finalized by year-end, the paper reported, citing people familiar with the matter. Representatives for the two companies didn’t immediately respond to messages seeking comment.

A combination could create a powerful challenger to rivals UnitedHealth Group Inc. and CVS Health Corp. Yet the size of the combination still wouldn’t approach that of UnitedHealth Group Inc., the largest insurer with a market value of almost half a trillion dollars. Cigna’s market cap is about $80 billion while Humana’s is about $63 billion.

The deal would likely face antitrust hurdles in an industry where the last two major combinations were both blocked by regulators. Those were a proposed tie-up between Cigna and Anthem, now Elevance Health Inc., and a separate deal for Humana to combine with Aetna Inc.

But Cigna and Humana have distinct focuses, which could help appease antitrust concerns. Humana sells mostly Medicare Advantage plans to seniors and has said it is going to stop selling employer coverage, where Cigna is strongest. Cigna’s Medicare business is small by comparison.

Cigna shares fell as much as 6.2%, the most intraday since August, while Humana was down 0.7% at 12:33 p.m. in New York. The news sent rival Centene Corp., which had been seen as another potential target for Cigna, down as much as 6.7%.