The most amazing part of such stories is how do they get such huge allocations on such basic strategies.
This is simply an example of what can happen with concentrated risk, and it's not very surprising, since many hedge funds seek to outperform an index with such strategies.
She had 20% of her fund in ONE stock, hence the concentration of risk (and gains when it was up, losses when it went down). Other hedge funds also had concentration risk in Valeant such as Ackman's Pershing Square fund, however not as much as Ratan.
I don't follow the stock, although it's had some negative news headlines on their failed attempts to overtake Allergan, among other things. If she had done simple technical analysis, the stock was a SELL when it breached $200, as there was a gap below around $175 which filled and then failed to rally back.
This article states that her losses are still paper, meaning she hasn't sold all of the position, although she did pare it down to 10%. Basically, she held too long and got greedy.
Despite the loss, it seems the fund has done well since its 2009 inception, so it's all relative to the
overall net annualized gains that investors have in the fund.
http://www.valuewalk.com/2015/11/tiger-ratan-valeant-vrx/