Analysts at Brown Brothers Harriman explained that the Australian dollar appreciated by nearly 4.3% last week to reach its highest level since the middle of last year. Key Quotes: "It is the biggest weekly advance since late-2011. Favorable economic data, a central bank that is in no hurry to cut rates again, and a recovery in commodity prices, including iron ore, copper, and gold underpinned the Australian dollar. Speculators in the CME futures market went net long the Aussie three weeks ago. Although the momentum story may be compelling, there may be too much of a good thing. Technically, the Aussie finished above its upper Bollinger Band (which is near $0.7360) and was near three standard deviations from its 20-day moving average ($0.7450). There have been two consecutive closes above the Bollinger Band. The last time this happened, it marked a multi-week high. Moreover, as the currency appreciates, the central bank is likely to express its disapproval. An appreciating Aussie may boost the chances that the rate cycle is not complete. " For more information, read our latest forex news.