Aug 7 (Reuters) - Billionaire investor Carl Icahn on Tuesday urged Cigna Corp shareholders to vote against the health insurer's $52 billion acquisition of Express Scripts Holding Co .
Icahn, who has a long position on Cigna and a short position on Express Scripts, said in a letter here that Cigna is overpaying for Express Scripts.
Last week, Cigna said it was confident of winning shareholder approval for its Express Scripts deal. The shareholder vote is due on Aug. 24. (Reporting by Ankur Banerjee in Bengaluru; Editing by Sriraj Kalluvila)