Pfizer and Allergan to Merge in $160B MegadealU.S biopharmaceutical company Pfizer Inc. and Ireland-based Allergan plc announce they will merge, in a historic $160 billion deal that could allow Pfizer to escape U.S. corporate tax rates by moving its headquarters to Dublin. PGT Healthcare and Swisse Wellness Join Forces GloballyThe agreement will make the Swisse Wellness range of vitamins and supplements available in Europe, Asia and Latin America over the next few years.