Wall Street shares fall after yuan devaluation worries investors

(Close): US stocks fell sharply after China's surprise devaluation of the yuan, sending the currency to a three-year low against the dollar.

The move hit US companies exposed China and heightened worries about the health of the world's second largest economy.

Commodity prices also fell in reaction to the strengthening of the dollar.

The Dow Jones fell 212.33 points, or 1.21%, to 17,402.8, and the S&P 500 lost 20 points, or 0.96%, to 2,084. The Nasdaq end down 65, 1.27%, at 5,036.79.

Apple fell 5.2% and General Motors closed 3.48% lower on concerns that both companies' could be impacted by the devaluation. Alibaba was another casualty, down 3.9%.

Oil prices were down, with US crude falling 4% to $43.08 a barrel, its lowest since March 2009. That pushed down oil related stocks, with Exxon Mobil dropping 1.6%.

"Obviously this devaluation seems to suggest there's a lot of weakness, and we're in thinly-traded markets right now," said Eric Kuby, chief investment officer at North Star Investment Management.

"To a certain extent, the stocks that have propped up the market this year have slowly fallen out of favour, so I think that you're seeing a little bit of a flight to safety," he said.

Google provided one of the bright spots on the market, with its shares rising 4.1% after it announced a major restructuring, creating a new parent company called Alphabet Inc.

Under the rebranding, Google will retain its best-known businesses, such as search, apps, YouTube and Android.

Some of the newer entities, such as the investment and research divisions, the "smart-home" unit Nest, and the drone arm will be run under Alphabet.