A grey wave describes an investment or company thought to be profitable in the long term or extended long term. Speculators of grey waves will buy an investment vehicle that they believe will show a return in the very long term, and not before.
The term grey wave can be explained by the understanding that when buying into a grey wave company, the investor should not plan for an immediate or even short-term positive return but, instead, only when they are much older and have grey hair.
Grey wave describes investment in the company that will likely not yield a positive return until a long time has passed.
Grey wave investments are not suitable for all investor types. Often, portfolio managers buy stocks that are expected to yield a particular return within a particular time frame, typically three to five years.