Punjabi posted UUU's Dec 15 short position and as I recall it was up from the Dec 1 report but not significantly and certainly nothing to become alamed over - especially considering the massive volume during that period. Most of the shorting of UUU at this price level IMHO is done for technical trading reasons and the parties participating are not making a directional bet based on geopolitical or fundamental reasons. I believe there is broad agreement that as Japanese reactors come back on line, new builds need U308, and the megatons to megawatts program expires, the price of spot U308 will increase and that will make it a difficult environment for a directional short.
Moreover, scalpers are driving substantial trading volume in UUU. They'll load up on both sides of the bid/ask spread and then work a .005 spread block off the TSX. The anonymous trade designation is probably more important to the jockeying they do between themselves than it is as a proxy for providing information on market direction.