But with signs the housing market has entered bubble territory, those banks with the most Canadian exposure, like National Bank and Canadian Imperial Bank of Commerce ( TSX: CM ) ( NYSE: CM ), will be the hardest hit. At the end of its fiscal third quarter 2014, Canadian residential mortgages made up 47% of total loans under management or LUM, highlighting the impact a housing crash could have on the bank. National Bank is also heavily exposed to the commodities and energy sectors in Canada with 8% of its LUM originating in those sectors. This emphasizes the impact on National Bank's earnings with both sectors suffering because of softer commodity prices. These factors, in conjunction with its lack of offshore businesses will hurt National Bank's ability to continue growing earnings. In contrast, those banks with international exposure, particularly to the rapidly recovering U.S. economy or fast growing emerging economies of South America, have far better future growth prospects.