US stocks tumble as weak Chinese data rattles sentiment

US stocks sank deep in the red Friday as weak Chinese factory data and US home sales numbers outweighed Amazon's unexpected blockbuster swing into profit.

The Dow Jones Industrial Average shed 163.39 points (0.92 percent) at 17,568.53.

The broad-based S&P 500 dropped 22.50 (1.07 percent) to 2,079.65, while the tech-rich Nasdaq Composite Index lost 57.78 points (1.12 percent) at 5,088.63.

"Despite a blow-out earnings report from Internet kingpin Amazon.com and mostly better-than-expected results from some consumer stalwarts... an unexpected decline in US new home sales and a disappointing read on Chinese manufacturing output sapped sentiment," said Charles Schwab & Co.

Falling crude oil prices pressured Dow members Chevron and ExxonMobil, down 2.5 percent and 1.5 percent, respectively.

Insurer Anthem sealed a $54.2 billion deal to buy rival Cigna, in a further consolidation of the US health insurance industry in the wake of the US Affordable Care Act. Shares of both fell though: Cigna dived 5.6 percent 2.9 percent and Anthem 2.8 percent.

Amazon shares rocketed 10 percent after the company blew out expectations of a loss in the second quarter, reporting after the market closed Thursday a net profit of $92 million and a 20 percent jump in revenue from a year ago.

Amazon leapfrogged Wal-Mart Stores, the world's biggest retailer, scoring a market value of $247.04 billion compared with Wal-Mart's $230.53 billion. Walmart shares lost 1.3 percent.

Other big tech names sank: Google shed 3.2 percent, Apple fell 0.5 percent and Dow member Intel lost 1.9 percent.

Biogen plummeted 22.1 percent after the biotech company lowered its 2015 forecast, largely blaming slower demand growth for multiple sclerosis treatment Tecfidera.

Other biotech shares felt the pressure: Amgen shed 3.4 percent and Celgene lost almost 3.0 percent.

On the Dow, Visa was one of three gainers, adding 4.3 percent after its earnings beat expectations.

American Airlines plunged nearly 7.0 percent percent after reporting record quarterly profit of $1.7 billion for the April-June period and announcing a new $2 billion share buyback program.

AT&T rose 1.1 percent after its $49 billion acquisition of satellite broadcaster DirecTV won final regulatory approval, clearing the way for a new powerhouse in broadband and video services.

Bond prices rose. The yield on the 10-year US Treasury fell to 2.26 percent from 2.27 percent Thursday, while the 30-year slipped to 2.96 percent from 2.97 percent. Bond prices and yields move in opposite directions.