周五大盘出现的一个底部特征就是VIX/VXN sudden spike, 然后 VIX/VXN curve 出现 backwardation （when the price of the further expiration futures is LOWER than the price of the near term/current expiration future). 这种情况前面都没出现过。
一般这个curve 都是contango (when the price of further expiration futures is HIGHER than the price of the near term/current expiration future).
backwardation 的出现说明市场失去理智。以前spot oil price 变成负的那次， oil future curve 也出现了backwardation, 说明oil price is bottoming, the market is irrational = 底部信号。
即使周五不是底，离底也不远了。即使不买入也要hold and strong.
