So Why is the Yen Skyrocketing?

Normally, a disaster has a country's currency falling, but the earthquake, and the nuclear power plant problems have the value of the Yen hitting a post World War II high.

So, why is this happening?

Two words: Carry trade.

You see interest rates in Japan are very low, so some people borrow money in Japan, and invest it elsewhere at higher interest, and thereby pocket the difference in interest rates.

The risk here is that the loans have to be paid back in Yen and if the currency strengthens, then you can end up owing more than you borrowed, a lot more than what you borrowed, and because this is typically very highly leveraged, it means that you lose a lot of money.

What is happening here is the concern that Japan will cash in, or more likely stop buying, US treasuries, because they need to spend the money on reconstruction, which strengthens the yen.

As the ¥ strengthens, the hedgies decide that they need to get their cash back into Yen before it appreciates any more, and so magnifies their losses.

So while normal concerns push the Yen up, you also have panicked (is their any other kind) traders who are desperately trying to buy into a rising market, which pushes up the Yen, which panics the traders more, who try to sell more $AUS or South African Rands to buy Yen, which further pushes it up.

Rinse, lather, repeat.