as of 12/31/10 D.E Shaw has surpassed Ardsley to become #1 inst. holder with about 928K. Also, Vanguard became #3 by adding 435K shares, Oxford #4 by adding 202K+ shares. All this happened way before the recent short raid, probably around RegSho 1 time (Sep 28-Oct15) when the stock was in the $10 range.