Back in 2000, Glaxo Wellcome PLC and SmithKline Beecham sealed the $75.7 billion deal and, as a team, took the name GlaxoSmithKline plc (ADR) GSK. Their union followed a brief period of tension — what was described as a "bitter power struggle" — but the differences weren't insurmountable. The monolithic drug company has since powered through two decades and shows no signs of slowing — despite one investor's encouragement to part ways.