Comparing multiples to book or tangible book may not be the best alternative for Citi right now. If you instead look at price to basel 3 tier 1 capital used at Citicorp (i.e. excluding Holdings) and compare that to BAC and JPM, they are very similar (1.4x in all 3 cases). This makes sense considering that capital tied up at Holdings has a negative return now. However, this ignores the high probability that Holdings will break even in the near term as well as the pace of capital build up at Citicorp from earnings, DTA use and decline in Holdings RWA. Citi is on its way to massive over capitalization in the next 2-4 years and the stock price doesn't reflect it. This is perhaps reasonable given Citi's performance in the 2012 ccar (who knows if shareholders will get their hands on that excess capital) but it sill ignores the ~20% annual growth in basel 3 tier 1 capital that Citicorp can achieve in the next 3 years just by staying the course (i.e. using Wall Street consensus numbers, which assume modest earnings growth).
As a side note my work relates to investing in EM and I'm from Argentina. The issues going on there are specific to the country, I don't think the chances of contagion are high, but we'll see.