Stock market sinks amid fears over emerging markets
A trader works on the floor of the New York Stock Exchange (NYSE) on Jan. 30, 2014 in New York City (AFP)

US stocks opened sharply lower Friday amid persistent worries over emerging market economies and a handful of earnings disappointments by US companies.

About 40 minutes into trade, the Dow Jones Industrial Average tumbled 180.40 points (1.14 percent) to 15,668.21.

The broad-based S&P 500 fell 15.47 (0.86 percent) to 1,778.72, while the tech-rich Nasdaq Composite Index declined 34.03 (0.83 percent) to 4,089.09.

The US losses mapped the deep falls in European markets as global financial turbulence continues unabated.

Investors also punished companies with disappointing earnings and earnings forecasts, pushing Amazon, Chevron and Walmart lower.

Amazon sank 7.6 percent after earnings came in at 51 cents per share, well below the 66 cents forecast by analysts. Results were hit by a sharp rise in expenses.

Dow component Chevron fell 3.6 percent after earnings slumped 32 percent compared with last year and revenues of $56.2 billion badly underperformed the $63.1 billion forecast by analysts.

Walmart, another Dow component, fell 1.0 percent after warning that earnings for the upcoming quarter would be "slightly" below prior forecasts due to cuts in the US food stamp program and bad weather that kept US shoppers at home.

Google jumped 3.8 percent after reporting that revenues on "click" ads rose by nearly a third. Google also announced a new dividend payment.

Earnings at MasterCard were 57 cents per share, three cents below expectations, sending its shares down 5.4 percent.

Mattel tumbled 9.0 percent after earnings missed the $1.20 per share estimate by 13 cents due to a six percent decline in worldwide sales.

Social games company Zynga shot up 17.9 percent after announcing it was buying mobile game and animation firm NaturalMotion for $527 million.

Bond prices rose. The yield on the 10-year US Treasury fell to 2.66 percent from 2.69 percent, while the 30-year declined to 3.60 percent from 3.64 percent. Bond prices and yields move inversely.

[Image via Agence France-Presse]