We have it 3 instances before.
1. On the first week of Dec 2013 , there was a big bar erasing 3 weeks gain, after that it was Christmas rally, previous high not violated.
2. 3rd week of Jan 2014, the big bar erasing 4 weeks/one month's gain, previous high was taken out, hence another two candle lower.
3. Last week of July 2014, a big bar erasing almost 8 weeks/2months of gain, previous high not taken out.
4. As of now, this big bar erased 5.5 weeks of gain, previous high taken out.
Let's see if 2000 get taken out on Monday
P.S. On top of that, each time we see a there is a 200+ point going up :-)