Last month, Chief Executive Fred Green and Chairman John Cleghorn both quit after a boardroom coup, a rarity in Canada's conservative corporate culture.
Ackman, whose fund Pershing Square is Canadian Pacific's largest shareholder with a 14 percent stake, had been campaigning since January to unseat Green, arguing that only new leadership could boost the railroad's operating efficiency.
In February, Pershing had added Haggis, a well-respected Canadian businessman, to its slate of nominees to sit on Canadian Pacific's board.
Haggis was previously the president and chief executive of the Ontario Municipal Employees Retirement System (OMERS), and president and CEO of Alberta Treasury Branches, Canadian Pacific said in a statement.
He is currently chairman of the Alberta Enterprise Corporation as well as of C.A. Bancorp Inc, the company said. (Reuters)
