Yes, but that doesn't answer the question. Sure, it makes sense that there's not much reason to hold stock when the growth is negative. The question was: how do

Yes, but that doesn't answer the question. Sure, it makes sense that there's not much reason to hold stock when the growth is negative. The question was: how do you decide why the growth is negative? This is an important, because sometimes stocks dip for a day, and sometimes they dip for a decade. Knowing why would seem to be the best basis for investing.