Did you read any announcements, or just look at your charts?
I believe that whenever the charts show a sudden change in direction it's worth a look at the announcements around the time it changed. If there's a change of fundamentals you could be looking at the share price adjusting to its new neutral level.
Newcrest looks like an example of this. Crap dividend, subdued forward estimates, forecast headwinds, and now a disaster at Cadia.
Although Newcrest has other productive assets none of those produce the margin that Cadia does.
I hope you have a solid stop-loss set.
NCM Price at posting:
$19.86 Sentiment: Hold Disclosure: Held