Graham received his early education in the investment business working during summer holidays at his father's brokerage firm Oswald, Drinkwater and Graham Ltd. In 1976, he joined Wood Gundy Ltd., becoming one of the youngest stockbrokers in Canada. In 1979 he moved to London, England, where he was appointed resident manager of Lévesque Beaubien Inc., a firm of Canadian stockbrokers, dealing with U.K. and European portfolio managers investing in the Canadian capital markets. In 1983, he was appointed managing director of Lévesque Beaubien Inc. in Toronto with the mandate to grow the firm's presence outside of the Province of Quebec. During this time, Graham served on the boards of The Toronto Stock Exchange and the Canadian Securities Institute. In 1986, Graham led a group of partners to purchase Lévesque, Beaubien Inc. from the then controlling shareholder and proceeded to take the firm public. Following these transactions, Graham became the largest shareholder of the firm. In 1989, following the deregulation of the Canadian financial service industry, (note: #) the National Bank of Canada purchased 75% of the firm (with the balance held by Graham and fellow partners) and in 1999, the firm purchased First Marathon Securities, Inc. and was then taken completely private by the bank and changed its name to National Bank Financial. In June 2000, Graham became president of Wittington Investments, Limited, the principal holding company of the Weston/Loblaw Group. From 2017 to 2019, he served as vice chairman. During his time at Wittington, he has served in various different capacities, including director of
George Weston Limited (1996 – 2016),
Loblaw Companies (1998–2015), chairman of
President's Choice Bank (2000–2015), president of
Selfridges Group (2003–2017) and chairman of
Choice Properties REIT(2017 – 2020). Graham is the chairman, president and CEO of Sumarria Inc., which is the largest shareholder (along with the extended Graham Family) of Graymont Limited of which he is chairman. Graymont has production and distribution facilities for chemical lime, stone and precipitated calcium carbonate in Canada, the United States, Australia, New Zealand, Malaysia and the Philippines as well as a significant investment in the largest lime producer in Mexico and South America. Graham has been a director of Graymont since 1987 to the present and served as chairman from 2003 to 2008 and was reappointed in 2022. Graham has also served on the boards of
Power Corporation of Canada since 2001 and Bombardier Inc. since 2019. He is a former director of Brown Thomas & Company Limited, Garbell Holdings Limited, Gardiner Group Capital, Holt Renfrew & Co. Limited, Power Financial Corporation, Scott's Hospitality Inc., Scott's Restaurants Inc., Sulconam Inc. and Victoria Square Ventures Inc. ==Community involvement==