Citigroup (C) stock is up 38% for the year and has more than doubled over the last two years, outperforming both the broader market and the financial sector during this period. The recent outperformance is a welcome relief for investors, as Citi has been a long-term underperformer, with its 10-year returns trailing those of its peers by a significant margin. Moreover, the stock trades at less than a fifth of its 2007 highs. Citigroup has had its own share of issues, which is reflected in its long-term pri ...