argenex SE (ARGX) shares soared 11.7% in the last trading session to close at $440.59. The move was backed by solid volume with far more shares changing hands than in a normal session. This compares to the stock's 7.5% gain over the past four weeks.The sudden rise in the stock price was observed after the company announced that the FDA approved its subcutaneously administered Vyvgart Hytrulo (efgartigimod) for a second indication — chronic inflammatory demyelinating polyneuropathy (CIDP). The drug has been ...