Last week, major central banks all over the world released their semi-annual report on forex turnover. It showed that while trading in the U.S. has improved, it dipped everywhere else. Here are some notable figures:

According to the data, the huge dip was mostly caused by the decrease in forex swaps. Spot trading was still solid, as it rose a respectable 2%.

So why did so many countries record a drop in forex turnover?

You can blame it on the Bank of Japan (BOJ) and the Swiss National Bank (SNB)!

Many believe that overall forex activity suffered as traders feared intervention from the major two central banks. Remember, the Japanese yen and the Swiss franc are two of the most widely traded currencies in the market. With those two currencies being closely guarded by their central banks, market speculation and therefore activity, was dampened.

In contrast, markets in the U.S. showed a different pattern. Equities were up, which suggests that traders in the U.S. had quite an appetite for risk. This, in turn, led to an increase in forex activity in the region.

Down the line, I think there's a chance we could see a further decrease in forex turnover. The BOJ and SNB still have their currencies on a tight watch, and I don't see them loosening their grip any time soon. The threat of intervention is still very much alive.

We also have to consider that summer is just around the corner, and this could lead to a downturn in trading activity as traders take time away from the markets.

Of course, with so many major developments taking place, what with the Greek debt situation nearing a resolution, there's also a possibility that trading activity could pick up.

What we should keep in mind is that one number does not make a trend. While forex turnover dipped over the six-month period from April to October 2011, the long-term uptrend remains intact. For now, I think we'll have to wait for the next semi-annual report before we can make a truly meaningful conclusion.