DMD stocks weak premarket

• Today will likely be a downer for DMD-related companies in light of BioMarin's (NASDAQ:BMRN) poor showing at yesterday's Ad Comm meeting. In premarket trading, BMRN is down 4% on increased volume, Sarepta Therapeutics (NASDAQ:SRPT) is down 1% on light volume and PTC Therapeutics (NASDAQ:PTCT) is down 12% on light volume (Jefferies just downgraded it to Underperform).