Regarding the short volume for ANY:
I don't think the total short volume actually increased dramatically between 11/28 and 12/15 - or, more precisely, I don't think it increased by 382,000 shares, even though the short interest went from 890K to 1273K (a difference of 382k shares).
ANY merged with OVRL. As of 11/28, OVRL had a short interest of 577K. I assume that has to get "rolled into" the total ANY short interest. At a conversion (roughly) of 0.46 shares of ANY per share of OVRL, that's about 265K shares of ANY. That leaves "only" about 116K of new short shares between 11/28 and 12/15. That's still a decent increase, but only about 11% of the total volume in that time frame, and correlated with a substantial drawdown of ANY share price.
So, if indeed the OVRL short shares got converted during that time into ANY short shares, everything appears to be more or less on the up and up - no need to appeal to illegal manipulation, etc., as far as as I can tell (given all of the assumptions stated above).