Cheer BBB.
I looked right back to the beginning of 2012 for major shorting.
Huge short positions came in to play on 14 May 2012 (15-20% of the total stock on issue) and continued for a few weeks.
What did this spate of shorting co-inside with?
The settlement of the SIOC deal.
I believe a few months back someone (can't remember who) posted SIOC was involved in this shorting.