Nothing mystery about the trades - it was simply UBS acting on a very, very wealthy clients order.
The UBS client had about $200 million worth of sell orders across several A-D blue chips.
He/she advised UBS to remove about $144 million of the sell orders 5 seconds before the end of the opening auction.
So the buyers were expecting to be matched with $200 million worth of stock ended up being matched with only $56 million worth of stock, which naturally pushed the opening price higher.
No glitches, fat fingers, algorithmic or HF trading involved.
