iPath S&P 500 VIX Short-Term Futures ETN (VXX)

[risk on]

The reason VXX or VIX aren't taking off, is due to the fact that it's based on short term options, specifically put: call ratios. So this is indicative of the not a large put interest , yet. Meaning the sentiment is that spy will not drop much more in the very near term, and may in fact rise, but that is not always accurate.

If, BIG IF, Apple hits a snag later today, that sentiment will shift in a hurry.