We analyse a sample of 6 million firm-year observations of large corporations and small and medium sized enterprises (SMEs) spanning 6 European countries from 2005 to 2015, to determine the impact of leverage and different sources of funding on default risk. We find that financial leverage has a greater impact on the probability of default of SMEs than of large corporations. The difference in default probability between the top and bottom leverage quartiles is 1.24% for large firms and 2.87% for SMEs. This difference may be explained by the greater exposure of SMEs to short-term debt and their consequently higher refinancing risk. Indeed, we find that SMEs that recover from the state of insolvency may have similar leverage to defaulted SMEs; however their liability structure is significantly altered towards long-term debt and away from short-term debt. Our findings have important implications not only for bank regulators and policy-makers but also for credit risk modelling.