It was probably not UBS in its own capacity, I guess that was one broker/insto sold to another broker/insto (One block sale 2.5m @48c on 18 July 2016) via UBS Securities. So UBS was more likely just acting as a stockbroker in this case. IMO. It could be Bank Of America sold their holdings to other broker/insto.
Net short positions was sitting at almost two-month low last Friday.
I expect further closure on shorts this Monday as sell-off is much smaller now.
