If you look at the NASDAQ afterhours trading log for INTC on the nasdaqDOTcom site, there was a flurry of activity at that price about 16:37.
There were several several 2m share trades and there were several marked as CANCELLED. There were none on the after hours log for 66m shares so that is likely a market maker settling trade to clear their books for the day.
I have never seen a cancelled trade likt that but the volume did pop from 30m to 100m at the end of the day. Intel can buy 25% of the volume and there is a 1 block trade exception on the buyback. My first thought is the Intel buyer taking a 66m block.