I just discovered that TrView has a very neat tool for applying fibo ratios to trend duration. Called "Trend-based Fib Time".
Since the duration of the correction often lasts 61.8% of the trend, there we have it - NIKKEI (and others) seem to be approaching this very milestone. It looks like a shorting opportunity to me.
NIKKEI is a high beta index, offering larger swings than SPX, so why not give it a try?