53 thousand shares is about twenty days of average volume. I have to believe that these borrowed shares are part of some sort of hedging strategy on the part of NWLI mgmt., because it would be madness for a stock trader to be significantly short a stock like this.
I tend to agree with your last statement regarding the short position. However, not all traders are rational and they may have made good money on the way to about $130. Short covering could help to explain the volatile movements in the stock but I do not have any direct evidence that it has. We will see what happens.