"Our firm, Glenview Capital Management, is a 10-year investor in Cigna, and we support the Express Scripts transaction," Robbins said in a letter to Cigna shareholders Thursday. "Together, Cigna and Express Scripts will save their customers billions of incremental dollars annually with better healthcare outcomes, consistent with the social mission of each entity."
Cigna announced the $54 billion deal for pharmacy benefit manager Express Scripts in March amid a wave of consolidation in the health-care industry. Cigna rival Aetna had agreed to combine with drugstore chain and pharmacy benefit manager CVS Health months earlier in a deal that shook up the space.
The investor noted Cigna is getting Express Scripts at an attractive price that is 25 percent below historical transaction valuations for similar companies.
"Sensationalist headlines and intentionally misleading assertions from those with conflicting interests and limited analysis should not carry more weight than balanced diligence," Robbins said.
Robbins said his firm has an approximately $1.3 billion total investment in Cigna and Express Scripts, split about evenly between the two companies. Icahn has 0.56 percent of Cigna, worth roughly $250 million, The Wall Street Journal reported. Icahn also has a short position in Express Scripts.