Apple sank nearly 4 per cent after the company pulled a software update for the iPhone after users complained that they weren't able to make calls.
The Dow Jones industrial average slumped 264 points, or 1.5 per cent, to 16,945 Thursday. That wiped out the Dow's gain of 154 points the day before. The index down 2 per cent for the week.
The Standard & Poor's 500 fell 32 points, or 1.6 per cent, to 1,966.
The Nasdaq composite, which is heavily weighted with technology stocks, fell 88 points, or 1.9 per cent, to 4,466.
U.S. government bond prices rose sharply as investors sought safety. The yield on the 10-year Treasury note fell to 2.51 per cent.