Not all deals are winners. Some, like Rio Tinto Group’s purchase of aluminum titan Alcan Inc. for $38-billion back in 2007, are downright disasters. It was Canada’s largest acquisition – a big bet on aluminum prices – and last week Rio Tinto had to take a second major writedown on the business.

Flops such as these aren’t the norm, but the big hits are few and far between. While most senior finance executives in Canada rate their most recent mergers and acquisitions somewhat positively, few deals are described as “very successful,” according to a Canadian Financial Executives Research Foundation study conducted in partnership with Towers Watson.