Ionis Slumps, Rival Alnylam Soars as GSK Decides Against Trial

Updated on
  • Ionis drops as much as 36%, biggest decline since March 2003
  • Alnylam, developing similar therapy, rallies for second day

Ionis Pharmaceuticals Inc. plunged the most since 2003 after GlaxoSmithKline Plc decided not to test a drug the companies were developing together. Alnylam Pharmaceuticals Inc., which is developing a rival therapy, soared on the news.

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