The BIS Quarterly Review for September 2013 says markets precipitate tightening.
http://www.bis.org/publ/qtrpdf/r_qt1309.htm Market volatility and foreign exchange intervention in EMEs: what has changed?
Huge swings in capital flows to and from emerging market economies (EMEs) over the past five years have led many countries to re-examine their foreign exchange market intervention strategies. Quite unlike their experiences in the early 2000s, several countries that had at different times resisted appreciation pressures suddenly found themselves having to intervene against strong depreciation pressures. http://www.bis.org/publ/bppdf/bispap73.pdf