NovoCure's stock experienced a significant pre-market plunge of 7.40% on Thursday. The sharp decline followed the release of the company's fourth-quarter 2025 financial results and its guidance for the upcoming year.

The oncology company reported a Q4 net loss of $24.5 million, with gross margin declining to 76% from 79% in the prior year due to costs associated with new product rollouts and tariffs. Furthermore, research and development expenses rose 19% year-over-year to $60.9 million as the company invested in clinical trials. While revenue slightly exceeded expectations, the market reacted negatively to the continued profitability challenges and the company's projection for 2026 adjusted EBITDA to range between a loss of $20 million and breakeven.

The weak EBITDA outlook, coupled with the margin compression and increased operational spending, appears to have driven investor concern, leading to the pre-market sell-off despite the recent FDA approval for its Optune Pax device for pancreatic cancer.