Japan's Partners Have Had Enough of the Weaker Yen: Jim O'Neill

Being a currency isn't always easy. Sometimes they're asked to be weak. Weak can be good. But not too weak. That can be unneighborly, or cause inflation -- and if a currency weakens too fast, that might be a crisis. What's a currency to do?

For a long time, global investors have seen a weaker yen as desirable. Japan's stock market has rallied when the currency weakens and dropped when the currency strengthens. Yet recent falls in the currencies of emerging-market economies have caused alarm. That's so, by the way, even though in many cases their stock markets advanced. (By the end of January, for all the talk of crisis, emerging-market stock markets were among the few worldwide to have made gains.)