US stocks tumble as Apple hit by Icahn exit of shares

US stocks finished a volatile session sharply lower Thursday after investor Carl Icahn said he had sold his remaining investment in Apple, sending the tech giant's shares down 3.1 percent.

Icahn told CNBC he liquidated his remaining shares due to worries the Chinese government would thwart Apple's efforts to sell more iPhones and other gadgets in the world's second-biggest economy.

Icahn also said he was "extremely cautious" about US equities given the embrace by the US Federal Reserve and other central banks of low and negative interest rates.

"Icahn was really the turning point," said Mace Blicksilver, director of Marblehead Asset Management.

The Dow Jones Industrial Average fell more than 200 points, or 1.2 percent, at 17,830.76.

The broad-based S&P 500 tumbled 0.9 percent to 2,075.81, while the tech-rich Nasdaq Composite Index sank 1.2 percent to 4,805.29.

US markets had opened lower following government data showing weak US economic growth in the first quarter and a decision by the Bank of Japan against enacting more monetary stimulus.

Those moves were countered by the lift from merger announcements involving the medical devices company Abbott Laboratories and cable and media giant Comcast. The Nasdaq was positive and the S&P 500 near flat before Icahn's remarks.

Medical device maker St. Jude Medical soared 25.6 percent on news it reached a deal to be acquired by Abbott for $25 billion in cash and shares. Abbott fell 7.8 percent.

DreamWorks Animation, the studio known for its "Shrek" and "Madagascar" films, surged 24.1 percent as it agreed to be acquired by Comcast for $3.8 billion. Comcast fell 0.2 percent.

Pharmaceutical company Medivation climbed 7.9 percent after French drug giant Sanofi made an unsolicited all-cash $9.3 billion takeover offer for the company. Medivation, known for the lucrative prostate cancer drug Xtandi, said it would evaluate the offer. US shares of Sanofi fell 1.8 percent.

Facebook powered 7.2 percent higher after announcing that first-quarter profits tripled from the year-ago period to $1.5 billion. Facebook's strong results contrasted with disappointing earnings over the last week from Apple, Microsoft and other large technology companies.