What is the relationship between:
VXX, iPath S&P 500 VIX Short-Term Futures ETN
XIV, VelocityShares Daily Inverse VIX Short-Term ETN
Naively, I'd think that an equal-weight portfolio should return zilch, but instead the return is highly negative.
If I run the attached algo on:
SPY, SPDR S&P 500 ETF
SH, ProShares Short S&P500
I get something much closer to zilch return over the same time period.
Is there something different about the VXX-XIV pair, compared to SPY-SH?