The SPX high on 12/15/17 was in the 2679 area just marginally above the target zone.
This high was quickly followed by a rapid decline in the last half hour of trading on 12/15/17.
This rapid drop following an expected throw over of the upper - typical at the completion of an EDT ,
strongly implies the upside pattern is complete.
After an EDT is complete, there is usually a very rapid retrace back to the EDT point of origin - which in this case is SPX 2605.
The down side target could be reached as soon as 12/21 or 12/22.
Big US tax bill vote is expected 12/19 or 12/20.
As of 12/15 it is strongly believed that there are enough votes to pass the bill.
The chart included in this article text by Mr. Rivest shows complete clarity of such an event happening,... before the end of the year.
It would certainly be a rapid style event, and the break would be a sudden waterfall like move to the downside.
A move up to S+P 2690 in 12/18 trading .....would be just the perfect final push needed to the top,... before the decline event begins.
Thank you Mr. Rivest for this remarkably illuminating post.