NEW YORK(TheStreet) -- U.S. stocks posted the worst month since May 2012 as Amazon (AMZN) - Get Report, Wal-Mart (WMT) - Get Report, MasterCard  (MA) - Get Report and Mattel (MAT) - Get Report tumbled on disappointing quarterly results, and global equities slumped on renewed concerns that emerging market economies, led by China, are slowing more than expected.

  • The S&P 500 dropped 0.65% to 1,782.59, while the Dow Jones Industrial Average fell 0.94% to 15,698.85. The Nasdaq slid 0.47% to 4,103.88. The S&P 500 dropped 3.18% in January, which was the worst tumble since a 6.27% drop in May 2012. The Dow tumbled 4.88% in January, which was its biggest loss since a 6.21% drop in May 2012.
  • "I think people are pretty spooked at the moment, and you can't invest across the board," John Rutledge, chief investment strategist of Safanad, said in a phone interview. "There's a system wide anxiety that seems to be showing itself."
  • Market sentiment has been rattled as emerging market currencies have come under renewed pressure, including those from Hungary, Turkey, South Africa, Russia and Poland.
  • The world's largest internet retailer, Amazon.com, sank 11% after its fourth-quarter earnings and revenue missed Wall Street estimates. Google (GOOG) - Get Report gained 4% after posting fourth-quarter results that were mixed compared to Wall Street expectations. Toymaker Mattel dropped 12% after its revenue came in short of expectations.
  • Other key laggards in the S&P included MasterCard and Newmont Mining  (NEM) - Get Report, which shed 5.1% and 10.4%, respectively.   
  • U.S. consumer spending grew by more than expected in December though income growth was weak. Consumer spending, which accounts for more than two-thirds of economic activity, increased 0.4% in December after rising by 0.6% in November, the Commerce Department said Friday. Income was unchanged after rising 0.2% in November. 
  • The January Chicago Purchasing Managers Index fell for a third consecutive month, dipping to 59.6 with its employment component falling to 49.2. The prices paid component was its highest since November 2012 at 64.9. The Thomson Reuters/University of Michigan final January index of consumer sentiment slid to 81.2 from 82.5 a month earlier, narrowly beating estimates.
  • The FTSE 100 closed off 0.44% and the DAX in Germany retreated 0.72% as shares of European companies tumbled following their earnings releases. Furthermore, data showed a cooling of the eurozone inflation rate to a record low in January and a still high jobless rate for the region in December. In Asia, the Hang Seng finished down 0.48% while the Nikkei shed 0.62%. 

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-- Written by Jane Searle and Joe Deaux in New York.