US stocks sank Thursday led by Apple's 3.8 percent drop, amid a combination of worries over heady valuations and quarter-end profit taking.
The Dow Jones Industrial Average finished down 264.26 points (1.54 percent) at 16,945.80.
The broad-based S&P 500 lost 32.31 (1.62 percent) at 1,965.99, while the tech-rich Nasdaq Composite tumbled 88.47 (1.94 percent) to 4,466.75.
Apple's embarrassing problems with its new operating system and criticisms that its new iPhones are too easily bent sparked its fall.
Peter Cardillo at Rockwell Global Capital cited a variety of concerns behind the broader sell-off, including geopolitical issues and weak economic data.
But he also pointed to profit-taking as the third quarter draws to a close.
"Investors are closing their books and they might be cashing in on a lot of their profits," he said.
All 30 Dow blue chips fell, led by UnitedHealth and JPMorgan Chase, both down 2.3 percent.
Besides Apple, other tech shares took sharp turns downward: Twitter fell 3.0 percent, Yahoo 2.3 percent and Microsoft 2.2 percent.
Alibaba, the Chinese Internet giant that went public last week, continued to hold up well above its $68 IPO price. Shares lost 1.8 percent at $88.92.
Jabil Circuit, which provides advanced electronics to computing, aerospace and other industries, dipped 2.2 percent as the company confirmed its 2015 core earnings forecast of $1.65-$1.95.
Bond prices rose. The yield on the 10-year US Treasury fell to 2.51 percent from 2.57 percent, while the 30-year dropped to 3.22 percent from 3.28 percent. Bond prices and yields move inversely.