Citigroup Inc. (NYSE: C ) operates in more than 140 countries and territories around the world and is one of the Big Four Banks in the United States, along with Bank of America Corp (NYSE: BAC ), JPMorgan Chase & Co. (NYSE: JPM ) and Wells Fargo & Co (NYSE: WFC ). My confident Buy rating on C is driven by an ongoing efficiency enhancement from improvement in credit quality, core revenues and strengthening capital ratios. In compliance with Basel III, management is on track to reach its target of greater than 10% Tier 1 common ratio by the end of this year, as it has increased from 7.2% to 9.3 YoY. Core capital generation increased from $4.6 billion to $6.3 billion.