I am not an expert, but It looks to me like the 2.5+ million share MOC sell was part of the automatic quarterly rebalancing of the GDXJ EFT (which matches the Market Vectors GDXJ index). The rebalancing happens on the 3rd Friday of the quarter-ending month. I noticed that the AUN shares in GDXJ were reduced by 2,744,246 to 32,556,108 shares. The rebalancing has nothing to do with whether AUN will go up or down in the future, but is based on a complex (to me) weighting and capping formula that is automated.