It used to be the P/E was low because people were nervous about Apple's future. Now people are nervous because they can't figure out how to evaluate the growth potential of a $1 tril+ company.

To my limited sophistication as an investor (who owns some AAPL), it seems to me Cook has tried several things to increase stock stability. One is to make it look a bit more like a utility stock for those who wish to see it as one, such as by paying dividends. Another is to signal to the market they consider the stock to be undervalued via a their stock buyback program.