Citigroup (NYSE:C) is up just barely in the first hour and a half of trading, after the pounding it took yesterday after a negative and widely read Bloomberg article made the rounds. But with the markets trending back and forth between positive and negative territory already today, don't expect that slim gain to necessarily hold.

Surprise, surprise
The Bloomberg article cited analyst Charles Peabody as saying that Citi could potentially be on the hook for a big loss on currency swings in the year ahead. According to Bloomberg: "[Peabody] estimates the bank may lose $5 billion to $7 billion in regulatory capital this year if the dollar gains against the yen, euro, and currencies in emerging markets."

Peabody is head of research at Portales Partners LLC. Bloomberg tracks 34 Citi analysts, and he is one of four who rates Citi a sell. Peabody is known for his prescience in seeing the coming collapse in the mortgage market.

Foolish bottom line
Citi shares were very volatile yesterday on this news, up and down all day. It doesn't help that the markets themselves are acting with great hesitancy and nervousness right now.

Fears of the coming drawdown of quantitative easing are leaving investors in a strange conundrum: When good economic news is reported, do you show your approval by investing more and boosting the markets, or do you withdraw your money and tank the markets, in fear of the consequent and certain coming end of QE?

And the Bloomberg/Peabody effect is interesting because it is just one analyst's report, although apparently a smart and well-respected one. But Peabody is still just one analyst, and his effect on Citi's stock performance is telling: Five years on from the financial crisis, it still doesn't take much to send certain bank stocks into a tizzy. Bank of America (NYSE:BAC) is the other, even more obvious example. Investors are still unsure whether or not banks like B of A and Citi are fully back on their feet.

But remember that Citi has this exposure to the currency markets because it has significant global operations. For the first quarter of 2013, 53.1% of Citi's revenue came from overseas. And in the end, I believe this is going to be the superbank's strong point.

Even in the post-crisis world, where some countries are trying to ringfence their banks' operations to minimize the kind of cross-border contagion that spread so rapidly in 2008, ultimately, globalization isn't going anywhere. There's money to be made overseas, and Citi is going to be there, while banks like Wells Fargo are staunchly defending their positions as domestically focused. I think that's shortsighted.

Again, Charles Peabody is in the minority on this viewpoint. I'm bullish on Citi for a variety of reasons, but I think its global operations are the bank's secret sauce. Yesterday was a blip, aided by market uncertainty. So tune out market noise like this, and tune into the fundamentals of the companies you're invested in. Your portfolio will thank you, even if your broker won't.  

Fool contributor John Grgurich owns shares of Citigroup Follow John's dispatches from the not-so-muddy trenches of high-finance and big-banking on Twitter @TMFGrgurich.

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