In the following video, Motley Fool financial analysts Matt Koppenheffer and David Hanson discuss Citigroup (C 2.21%), and how it gave investors a very pleasant surprise in last night's Dodd-Frank bank stress test results. While the company failed the CCAR stress test results last year, embarrassingly, this year, Citi's capital levels have improved dramatically. Matt tells us about the metric that shows just how much Citigroup's capital levels have improved, and what this means for investors.