Apple's slowing growth worries investors

Shares of the iPhone maker have been in a rut since posting disappointing quarterly results in late June, falling to a six-month low of $113.25 on Tuesday.The recent declines have wiped out nearly $100 billion of Apple's market value - about as much as fellow Dow components Boeing and McDonald's are worth in total. For CEO Tim Cook, it means his stake of more than 111 million shares is now worth about $12.76 billion, compared with nearly $15 billion at the peak in late April.The dropoff represents a notable bout of weakness for a stock basically impervious to pain for the better part of two years.