Elan Corp. plc (ELN) and Biogen Idec Inc. (BIIB) gapped open lower on Friday and held a range for the rest of the day.
The move followed news of two confirmed cases of progressive multifocal leukoencephalopathy or PML in multiple sclerosis or MS patients treated with Tysabri in the commercial setting.
Elan ended the session at $9.93 down $10.12 from Thursday's close. The stock closed at a new multi-year low.
Biogen ended the day at $50.01 down $19.75 from Thursday's close, its lowest level in over a year.
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June 05, 2026 16:18 ET A busy week for economic news flow saw a slew of reports being released that reflected the trends in the U.S. labor market. In Europe, economic growth and inflation data gained attention as the European Central Bank and Bank of England head for policy session later in the month. In Asia, the monetary policy session of the Indian central bank was in focus as the country, a major oil importer, reels under the pressures of a weaker rupee and rising inflation.