Sionna Therapeutics Inc. has opened on Nasdaq in the year’s fourth IPO, this one priced at the upper end of its original per-share range at $18. The cystic fibrosis therapy developer is looking for gross proceeds of about $191 million by offering 10.58 million shares of common stock. On Feb. 7, shares (NASDAQ:SION) closed the day 39% upward at $25.