Argenx SE (ARGX) saw its stock price soar 5.07% during intraday trading on Monday, following a significant regulatory milestone announced over the weekend.

The surge comes after the company announced it secured U.S. Food and Drug Administration approval for a label expansion of its drugs Vyvgart and Vyvgart Hytrulo. The approval extends the use of the treatments to all serotypes of adult patients living with generalized myasthenia gravis.

The regulatory decision was supported by positive data from a phase 3 trial, which demonstrated rapid, significant, and sustained improvements in symptoms across serotypes. This expansion is expected to broaden the addressable patient population for the company's flagship products.