A Wall Street hedge fund pitched Bay Street investors Monday in an effort to get fellow CP Railway shareholders on board with a plan to turn the company around.

Pershing Square Capital, a N.Y.-based hedge fund led by financier William Ackman, has been pushing for months to replace Canadian Pacific Railway CEO Fred Green with Hunter Harrison — the retired CEO of CP's main rival, Canadian National Railway.

With a 14.2 per cent stake, Pershing is CP's biggest single shareholder. Ackman contends that CP's stock has underperformed for the entirety of Green's helm as CEO, and he wants to bring in new management to turn the company around.

Including dividends, CP shares have returned minus 18 per cent since 2006, Ackman told investors at a conference in downtown Toronto on Monday. "The results, by a longshot, are the worst performing railroad in North America," Ackman said.

Ackman's plan centres on ousting Green and installing Harrison as the new CEO of Canadian Pacific. He would also like to add new members to the company's board.

"I like this board, but the CEO they've decided to work with isn't working," Ackman said. "Eventually you have to let them go if they're not doing the job."

"If we don't fix this now the business is at risk," Ackman said.

The Tennessee-born Harrison was once named Railroader of the Year by an industry trade publication and has a reputation for making trains run efficiently. He has twice led turnarounds of railway firms in his four-decade career.

Ackman quietly approached Harrison in August, trying to get him to come onboard at CP.  Harrison retired from CN on Dec. 31, 2009, and signed a non-compete clause that prohibited him from working for a competitor for two years. But since that expired in January, he has gotten more vocal about his interest in the top job at his former rival.

CN has fired back at the plan, moving to end Harrison's pension payouts and a series of other payments worth roughly $45 million.

"CP is a wonderful franchise with a lot of opportunity," Harrison said. "It's right in my wheelhouse."

Harrison said he believes CP has a bright future if inefficiencies in the company's network can be fixed. On Friday, Harrison said he made a personal investment of $5 million worth of CP shares to show how confident he is in the company.

Pershing Square says it is time for "real change" at Canadian Pacific" because of "serious concerns" regarding current management. Green has earned more than $27 million in salary and benefits since taking the helm, even as the stock has lagged.

"There's more and more money going to senior management while the company does worse and worse," Ackman said. "This makes no sense."

Canada's largest banks, including RBC Global Asset Management, BMO Capital Markets and TD Asset Management also own CP shares. Representatives from all were in attendance at the meeting, as was Alberta's pension fund manager, AIMCo.