On Friday of last week, the USDJPY opened in the 155-yen range and continued to rise all day towards the close, surging to hit a high of 158.44.

At the Bank of Japan Monetary Policy Meeting on that day, the BOJ, as expected, decided to leave its policy rate unchanged.

Today the USDJPY started trading by gapping down by around 50 pips at the open, but this was quickly filled and the price subsequently continued to rise. Although the price broke into the 160-yen range at around GMT 01:35, this turned out to be the peak and the price began to plunge. By a little after GMT 05:00 the decline from the highest point had exceeded 500 pips, but it is unclear whether this slump in the price was caused by currency intervention.

Looking at the 1-hour chart of the USDJPY (as of GMT 06:50 on April 29), the price plunges from the +2 standard deviation Bollinger Band through the -2 standard deviation without a pause.

(20-period Bollinger Band, showing ±1 and ±2 standard deviations)

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