On Friday's news that Biohaven (BHVN -15.34%) withdrew its application for a top investigational drug from an important regulator, investors aggressively traded out of the stock. The clinical-stage biotech was one of the biggest decliners in its industry, exiting Friday with a share price decline of over 15%. This was during a session that was essentially bullish; the S&P 500 index closed 0.6% higher. Strategic withdrawalThat news came not from Biohaven itself, but from the European Medicines Agency (EMA, t ...