The Canada Pension Plan Investment Board reported its lowest annual rate of return since 2009 on Thursday and said its head is leaving the national money manager abruptly to take a job at private sector investing giant Blackrock in about a month.

Mark Wiseman, who has held the top job at Canada's national pension plan for four years, will step down on June 13, CPPIB said in a statement. The board manages the assets not required by the fund to pay benefits for its 19 million members. As of the end of March, CPPIB had almost $280 billion under management, a figure that has grown by $100 billion under Wiseman's leadership.

Wiseman's departure was announced the same day that CPPIB said its annual rate for return dipped to 3.4 per cent last year, its lowest since it had a decline of 18.8 per cent back in its 2009 fiscal year. In its 2015 year, the CPPIB posted a rate of return of 18.3 per cent, which followed 2014's return of 16.1 per cent. 

"Over the past twelve months, despite one of the more challenging investment environments in recent years and predominately negative equity markets, the CPP Fund generated a moderate gain," Wiseman said. 

Biggest money manager

In his new job, Wiseman will head up the global active equity business at Blackrock, the world's largest money manager, with $4.7 trillion assets under management.

In his place, CPPIB's senior managing director Mark Machin will ascend to the CEO's role at CPPIB.

Under Wiseman's leadership, the CPPIB has grown its head office in Toronto and added offices in other financial centres, including one opened last year in Mumbai, India as the fund has taken on a distinctly international focus in search of returns to be able to cover its growing domestic obligations.

Currently, the percentage of the CPP Fund that is invested outside of Canada has risen to approximately 81 per cent. The remaining 19 per cent, or about $53 billion, is invested in Canada.