This analysis builds on certain aspects of prior studies, but important limitations remain and these results should be interpreted with caution. GAO's estimates of differences in funding costs reflect a combination of several factors, including investors' beliefs about the likelihood a bank holding company will fail and the likelihood it will be rescued by the government if it fails, and cannot precisely identify the influence of each factor. In addition, these estimates may reflect factors other than investors' beliefs about the likelihood of government support and may also reflect differences in the characteristics of bank holding companies that do and do not issue bonds. Finally, GAO's estimates, like all past estimates, are not indicative of future trends.