So far, investors don't seem to be too worried about a US government shutdown... or anything else for that matter. In fact, overall volatility is still sitting at historically low levels. The CBOE S&P 500 Volatility Index, or the VIX, is trading just over $14. The long-term historical average of the so-called fear gauge is right around $20. Basically, when the VIX is under $20, investors don't believe a market meltdown is on the horizon. For the vast majority of 2013, the VIX has been well under $20 - and it's true, the market has been relatively calm this year. However, if we start to see a spike in the VIX, particularly if the index trades over $20, it may be time to consider lowering risk exposure. Let's see what happens to the VIX as the looming government shutdown approaches.