Fundamentally: CPI was released. Traders felt it was negative for Gold and sold it.
Technically: An Ascending Triangle which began on September 7th.
This was a range between 1691.83 to 1729.52.
The trend line was respected apart from two false breakouts. The resistance was also respected other than a false breakout at the top-which could be considered an Upthrust because of its consequential effect.
These two happening together created a perfect situation to short.
The primary move happened within the first minute of CPI being released.
I wish I had followed my gut and traded instead of being away from the computer for this event.