French biotech Abivax is the best-performing stock in the Stoxx 600 this year – by a significant margin. Shares are up 1,441% so far this year, a staggering number, even for a clinical stage biotech, known for its price volatility and high-risk. By comparison, the next best performing stock is British mining company Fresnillo , up 373% year to date. Abivax’ rally started with a 510% gain on July 23, the day after the company reported data on a late-stage trial of its lead asset obefazimod, a treatment for ulcerative colitis. Since then, the stock has continued to climb amid investors’ optimism around the company’s pipeline, as well as unconfirmed rumours of a takeover bid from a larger peer. ABVX-FR YTD line Abivax shares have soared in 2025. “We are always [in] conversation with Big Pharma,” CEO Marc de Garidel told CNBC’s “Europe Early Edition” on Tuesday, but emphasized it is largely out of his company’s control. “We don’t control what the big companies will do. But we are certainly excited about the work we are doing, and we’ve been greeted again by the medical community as becoming possibly [the] next standard of care in ulcerative colitis,” he said. The trial results presented in July had tested the drug for eight weeks in patients with moderate to severely active ulcerative colitis, a type of chronic inflammatory bowel disease. The company plans to report the effects of a full-year treatment in the second quarter of 2026. A catalyst-rich 2026 Abivax has a number of potential catalysts coming up in 2026. For its lead asset obefazimod, Abivax is planning to file for regulatory approval next year. “Hopefully that will mean a launch in Q3 of 2027 in the United States,” said De Garidel. Beyond ulcerative colitis, the company also has a mid-stage program for Crohn’s disease, another inflammatory condition in the digestive system. It is planning to report the results of those trials by the end of 2026. But the company is bleeding money. As it doesn’t generate any revenue, net loss widened significantly in the first nine months of 2025 to 254 million euros ($298.6 million), up from a loss of 137 million euros last year. That was largely driven by the costs of running the obefazimod one-year clinical trial, De Garidel told CNBC. Research and development expenses increased to 133 million euros, up from 108 million euros in 2024, the company said after market close Monday. Abivax shares fell about 8% by mid-morning Tuesday, making it the worst performer in the pan-European blue chip index. Abivax raised nearly $750 million this summer through a public offering of American depositary shares on the Nasdaq stock exchange, which De Garidel said allows it to be financed until the end of 2027. Still, there is some speculation that Abivax might be looking to sell the business. Those rumors have further boosted the stock, according to reporting by Reuters that identifies U.S. pharma giant Eli Lilly as a potential suitor. CNBC has reached out to Eli Lilly and Abivax for comment. M & A action in the biotech sector has also picked up significantly over recent months as a number of headwinds for biopharma have eased, including pricing pressure in the U.S. and the threat of high sector tariffs. The annual J.P. Morgan Healthcare Conference, taking place in San Francisco on Jan.12-15, is often a key event where companies often make announcements. At the conference, Abivax will look to “explain why the ulcerative colitis market may expand actually much faster than what we thought, thanks to the profile of obefazimod and possibly also the profile of another competitive drug,” according to its CEO. — CNBC’s Silvia Amaro contributed to this report
