Cystic fibrosis investors came to learn a harsh lesson on August 10 about how concentrated a market can be: Sionna Therapeutics, Inc. (NASDAQ:SION) shares fell more than 90% following a key trial failure, while Vertex Pharmaceuticals (NASDAQ:VRTX), the company whose drug dominance Sionna…This story appeared on finance.yahoo.com , 2026-08-12 03:41:31.