This was Quad Witching Day across the board. It was all types of stocks beside miners that had the big after hours volumes. Even some on the Venture exchange with AUN as an example had 2.5 mil after hours and dropped 15%. There was actually massive volume on the open for some also. This happened a few months back and all returned close to EOD pricing the next trading day. I did email regulators about this and actually got a reply, some of it close to legible. In most cases it's fund adjustments.
Hope this helps and here's wishing everyone a Merry Ho Ho. I strongly feel that next year will see some substantial interest in our sector.