Cigna's pharmacy benefits unit Evernorth said the deal will bring prices down for employers and their workers.
The shake-up follows Novo Nordisk's leading position in the fat jab market coming under threat.
These are the stocks posting the largest moves in midday trading.
Days earlier, Novo Nordisk cut its sales and profit forecast for first time since the launch of Wegovy four years ago.
These are the stocks posting the largest moves in premarket trading.
Despite a late start, the American firm is bearing down on its Danish rival
These are the stocks posting the largest moves in premarket trading.
European markets were lower on Wednesday, with traders monitoring corporate earnings and awaiting the Federal Reserve's latest monetary policy announcement.
Starting July 1, Caremark will prioritize Wegovy on its formulary, making the weekly injection more accessible to its members.
European equities saw a sharply higher open, with investors still reeling from one of the wildest weeks for markets on record.