The U.S. Federal Trade Commission said on Wednesday it had sought information from two companies that negotiate drug rebates on behalf of pharmacy benefit managers (PBMs) as part of its probe into how PBMs affect pricing of prescription drugs.

The two companies, Zinc Health Services LLC, and Ascent Health Services LLC, are associated with CVS, Cigna's Express Scripts unit, and Prime Therapeutics, the FTC said.

(Reporting by Manas Mishra in Bengaluru; Editing by Vinay Dwivedi)