Bloomberg reported the news, citing trade publication Reorg Research. Aetna declined comment. CVS said it does not comment on "market rumors."
Drugstore chain and pharmacy benefits manager CVS announced in December it would acquire health insurer Aetna for $69 billion in a deal that could reshape the health industry. Some had feared the Department of Justice would seek to challenge the deal like it did AT&T's acquisition of Time Warner.
CVS shares rose nearly 3 percent, while Aetna's shares increased 2 percent. Shares of Cigna and Express Scripts also rose on the news. The health insurer Cigna is in the process of acquiring pharmacy benefits manager Express Scripts.
Express Scripts declined comment.
-CNBC's Bertha Coombs contributed to this report