Apple's decision to stop reporting iPhone sales data worries investors

One problem Apple investors will now face is not knowing what the margin mix is within the services business

First Apple Inc took away the headphone jack on its iPhones. Then it took away the home button.

And now, it has taken away a closely watched performance metric that it has disclosed to investors for 20 years.

The Cupertino, California-based company on Thursday said that it will stop reporting unit sales data for its iPhone, iPad and Mac computer products, the latter of which it has given out since 1998. Analysts and investors use the figures to calculate the average selling price of Apple's devices and gauge the health of the company.

Apple said the data is less relevant to the strength