Emerging markets are back in the spotlight. Investors and banks are suddenly unwilling to finance current-account deficits with short-term debt.

South Africa, for example, has had to increase interest rates, despite slow economic growth, to attract the funding it needs. Turkey's rate increase has been dramatic. For these and other emerging countries, 2014 may prove turbulent.

If volatility becomes extreme, some countries may consider constraints on capital outflows, which the International Monetary Fund now agrees might be useful in specific circumstances.