Biogen's second-quarter profit plummeted and the biopharmaceutical company cut its full-year adjusted earnings forecast.

Net income fell to $97.5 million, or 66 cents a share, from $634.8 million, or $4.33 a share, a year earlier. The company said results were hurt by deal-related charges, in-process research and development charges, its Apellis acquisition, and continued investment in Phase 3 programs.

On an adjusted basis, earnings fell to $3.60 a share. Analysts polled by Factset were expecting adjusted earnings of $2.94 a share.

"This quarter is a reflection of the significant progress Biogen has made repositioning the company for long-term growth," said President and Chief Executive Officer Christopher A. Viehbacher.

Total revenue ticked up 3% to $2.74 billion, compared with analysts' expectations of $2.46 billion.

Biogen said revenue from its rare disease drugs rose 11% in the quarter, though its multiple sclerosis revenue fell 13% and biosimilars revenue dropped 13%.

Looking ahead, Biogen expects full-year adjusted earnings of $12.00 to $13.00 a share, from a prior view of $14.25 to $15.25 a share. Analysts are expecting adjusted earnings of $12.63 a share.

The company also said its full-year total revenue is now expected to increase by a mid-single-digit percentage for 2026 as compared to 2025.