NFLX is another one of those that don't trade on any sense. The stock has come back from low-$50s to $77 today. And on what? Nothing. That is how one loses money shorting NFLX... the discount/momentum buyers run it up and spooks the shorts.
As for AMZN, how does it being down today NOT make sense? Retail sales numbers were weaker than expected. BestBuy stinks. Did you notice that AMZN "extended" their holiday shipping? Probably to make up for lower than expected sales. And you know what that means, squeeze on margins.