Sionna corona fades in CF as Street sweats phase IIA would-be competitor for Vertex Pharmaceuticals Inc. in cystic fibrosis (CF) blew up in phase IIa and shares of Waltham, Mass.-based Sionna Therapeutics Inc. (NASDAQ:SION) closed Aug. 10 at $4.50, down $46.54, or 91%. The Wall Street reaction came after Sionna disclosed top-line data from two nucleotide binding domain 1 stabilizer programs.