If a institutional investor sells, there are always a few small...

If a institutional investor sells, there are always a few small retail investors (Holders 'A') who conclude that the insto knows something, so they sell. However, there are always other holders (Holders 'B') who think the insto has sold for other reasons (portfolio balancing, etc), but they know that Holders 'A' are going to sell, so Holders 'B' sell, perhaps intending to reinvest at a lower SP. Then come the chartist and algorithmic players, who detect a negative pattern in the graph movements, so they sell. Then the panic sets in and a new wave of selling occurs. After a while, like all plagues, selling pressure is exhausted. Then an insto who probably does know something buys, and the foregoing chain of events is reversed.

Alternatively, some new Announcements trigger the SP recovery, followed by the chain reaction described above. I should have worked shorters into the chain of events too

It is difficult to know if SP movements reflect fundamental changes to a company – particularly as it is fairly usual for directors to lie. I have through much suffering caused by directors gilding the lily concluded that the ethics and capability of directors is one of the most important things to establish in investing. Many ex-directors of listed companies who now swan about as successful businessmen should be in prison, IMO.

If you believe in NWH's directors, then be guided by what they announce. In the case of NWH, and CCP, which I also hold, things usually pan out better than announced.