Pharmaceuticals were among the big fallers in early trading in Europe Friday, after reports that House Democrats started an investigation into the pricing of drugs for multiple sclerosis.

Drugmakers Biogen (BIIB) , Sanofi (SNY) , Novartis (NVS) , Roche Holding (RHHBF) , Bayer (BAYRY) , Merck KGaA (MKGAF) 's EMD Serono unit and Teva Pharmaceuticals (TEVA)   were among the companies that received letters requesting information on pricing strategies from Elijah Cummings and Peter Welch, two representatives who sit on the House Committee on Oversight and Government Reform, Bloomberg reported. 

The letters reportedly said some companies appeared to be "setting new higher prices in lockstep with competitors - a strategy known as 'shadow pricing'." They said the average cost of therapy had increased to more than $60,000 in 2015 from about $16,000 in 2004.

Sanofi was down 1.27% at €81.71, Novartis was down 2.05% at Sfr 81.15, Roche was off 0.53% at Sfr245.50, Bayer dropped 0.33% to €107.00, Merck KGaA was down 0.47% at €91.92 and, in Tel Aviv, Teva was off 1.13% at 6,362 Israeli shekels ($1,756.74). Biogen, the only U.S. company on the Democrats' list, closed down 3.28% in New York last night.

Merck KGaA is a German company and not to be confused with its U.S. namesake Merck & Co. (MRK) which has not been caught up in the probe.

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