Icahn further compared the situation at Illumina to the events leading up to the appointment of Steve MacMillan as CEO of Hologic in 2013. Back then, Icahn built up a 12.6% stake in Hologic and drove changes to the leadership team and board. Less than three years later, Icahn began cashing out after seeing the company's stock price rise in the wake of his activist intervention. MacMillan was recently named as non-executive chair of Illumina's board in the wake of Icahn's push for changes.