You are right. As GDX takes out the 200dma it's bound to trigger considerable profit taking amongst traders. A better explanation for today's action can't be found. There was no gaming between the metal and stocks. There was no gaming between gold & silver. When AU hits its own 200dma ($1311) the stocks will already be launched. As a consequence AU might not have so much as a hiccup at that point. A virtuous circle.