It's been a long time coming but some real profit taking in gold finally arrived.Gold tested $4000 again about an hour ago and this time it didn't hold. That led to a heavy round of selling that saw it quickly fall to $3945.I think it would be healthy to see gold scale back to around $3700 but the bulls have answered every challenge so far. This one -- not coincidentally -- is also coming alongside some selling in high-flying equities.Even more importantly, the US dollar is strong today following upbeat comments on the strength of the consumer from Delta Airlines. A reacceleration -- and re-heating -- of the US dollar would be something of a gamechanger in the current state of play in many markets, though gold certainly has multiple factors supporting it. This article was written by Adam Button at investinglive.com.