UPDATE: As an observation, QQQ Short-Interest is at 11 year lows (January 2001)
Curious what has provoked a vicious year end (and 2012 year beginning) Santa Rally, which until today had seen the S&P trade higher on 12 out of 15 consecutive days? Wonder no more: the reason is the same it has always been - year end short covering, which in turn has spilt over into the new year's momentum chasing HFT brigade and the occasional retail momo who still has some cash left after covering commission costs. According to the latest NYSE biweekly update, the short interest as of the end of 2011 was a modest 12.8 billion shares, a sharp drop from the 13.4 billion and 14.2 billion 2 and 4 weeks prior, and certainly a very far cry from the over 16 billion shares short which market the market bottom in late September. Also, for anyone wondering why so far 2012 is an identical replica of 2011, decoupling and all, look no further than the SI data as of early 2011 - SSDD. Short covered, and only as the year unwound did they dare to challenge the central banks and to increase their shorting activity.
As further evidence of what seems like a huge short-covering surge into year-end, QQQ (the NASDAQ ETF) saw short-interest drop over 43% into year-end to levels not seen since January 2001 (11 years!).