Google "vixcentral". This gets continuously updated with the spot VIX price and VIX futures.
The only relevant prices is VIX spot, and the first two futures. Usually there is a cushion of more than 8% percent between spot VIX and first month. So VIX can go up without VXX going up, just because the futures don't move.
But at end of day yesterday, spot VIX and the first month future was at the same price, so there was no contango. If the market normalizes VIX will go down faster than VXX so that the cushion gets normal (that is bigger) again. That's what happened today.
Benjamin72: You've noticed this today; for, many days, I have seen the VXX hardly move up when the markets are hammered but deteriorate rapidly when the markets are just slightly up. These last two days tells the story. Do not let Barclays people con you with this "contango." The ETF/ETN are as a mutual fund, where operating expenses are used from this. They are the ones who had been playing con-tango with the cookie jar.