Despite positive new pivotal data supporting its migraine treatment candidate, rimegepant, Biohaven Pharmaceutical Holding Co. Ltd. saw its shares (NYSE:BHVN) touch an all-time low Monday as investors fretted over the program's competitive stance in the crowded class of calcitonin gene-related peptide (CGRP) receptor antagonism. By day's end, the candidate's success in meeting the trials' co-primary endpoints appeared to soften the blow, leaving shares just 7.3 percent lower at $22.96.