Mainly, because we are still going through a transition phase typical of post-crisis periods. And, these transition stages – where key macroeconomic variables converge to their long-term values – take time and raise enormous challenges. For instance, it took long to countries such as Chile to fully stabilize their economies and achieve sustained growth.
When the turbulence deepened in early August, demands for liquidity and reserves pushed overnight rates in interbank markets above monetary policy targets. The aggressive  2  BIS Review 140/2007  provision of reserves by a number of central banks met those demands, and rates returned to targeted levels.