CVS Health Corp.’s drug-benefits unit negotiated a deal to make Novo Nordisk A/S’s Wegovy more widely available to its members, a blow to rival Eli Lilly & Co.’s Zepbound that was moved off the company’s list of preferred drugs.

Wegovy and Zepbound are part of a wave of obesity medications known as GLP-1 receptor agonists that have soared in popularity due to the amount of weight people lose while taking the injections. Coverage of these drugs has been patchy due to in part to their cost and the wide swath of patients who could take them.

Shares in Eli Lilly have weakened after CVS Health, one of the largest pharmacy benefit managers (PBMs) in the US, said it would no longer cover its obesity therapy Zepbound. The shares closed down nearly 12% after CVS Health's revelation and Lilly's announcement that,