A neat plot to show how overbought we are, with explanation

Ok people. Here it is. Now this is a plot that will need some explaining. Of course all of you know the S&P 500 index which is plotted on the right axis. The other graph plotted using the left axis is the ratio of the VIX to its 50 DMA (50 day moving average).

VIX (use ^vix is yahoo finance) measures volatility, or in simple terms, the fear factor in the market. When it gets really low, it means that there is not much fear out there. By itself, the volatility going low would not be an issue, but what is a big concern is that it has gone so much lower than the mean to the extent that it's not outside its 1 sigma std. deviation! This is serious optimism on the part of investors! An moreover, this doesn't even include today's datapoint!!!