CPPIB said on Friday it had accepted Machin's resignation and appointed John Graham as chief executive officer. : The head of Canada Pension Plan Investment Board, Mark Machin, has stepped down after disclosing he recently traveled to the United Arab Emirates where he arranged to be vaccinated against Covid-19, the country's largest pension fund said on Friday. CPPIB said on Friday it had accepted Machin's resignation and appointed John Graham as chief executive officer. Canada's Ministry of Finance on Thursday called a media report about Machin traveling to the Middle East and receiving a COVID-19 vaccination "very troubling".