Eli Lilly (LLY) shares plummeted 7.29% in pre-market trading on Thursday, following the release of its first-quarter 2025 financial results and amid news of a competitive setback in the weight-loss drug market. Despite beating earnings expectations, the pharmaceutical giant's stock took a hit due to lowered full-year guidance and a strategic move by CVS Health favoring a rival's product.

The company reported adjusted earnings per share of $3.34, surpassing analysts' expectations of $3.26. Revenue for the quarter reached $12.73 billion, slightly above the anticipated $12.67 billion. However, sales of Zepbound, Lilly's weight-loss drug, came in at $2.31 billion, just short of the $2.33 billion analysts had projected. Mounjaro, Eli Lilly's diabetes treatment, posted strong sales of $3.84 billion, showcasing a 113% year-over-year increase.

Despite the overall positive results, Eli Lilly reduced its full-year 2025 adjusted earnings guidance to between $20.78 and $22.28 per share, down from the previous forecast of $22.50 to $24 per share. This downward revision was attributed to a $1.57 billion charge related to acquired in-process research and development recognized in the quarter. Adding to the pressure on Eli Lilly's stock, CVS Health announced it would be taking a formulary action on July 1, 2025, to prefer Novo Nordisk's Wegovy for its members, potentially impacting Zepbound's market share in the highly competitive weight-loss drug segment. This move by one of the country's largest pharmacy benefits managers could significantly affect Lilly's position in the obesity treatment market.