 In 1907 he founded the Montreal Engineering Company.In 1909, also under the umbrella of his Royal Securities Company, Aitken founded the Calgary Power Company Limited, now the TransAlta Corporation, and oversaw the building of the Horseshoe Falls hydro station.In 1910–1911 Aitken acquired a number of small regional cement plants in Canada, including Sir Sandford Fleming's Western Canada Cement Co. plant at Exshaw, Alberta, and amalgamated them into Canada Cement, eventually controlling four-fifths of the cement production in Canada.