Afghanistan: U.S. Markets Tumble as Fear Spreads --- U.S. stocks tumbled Friday to their biggest loss in more than seven months, extending a global selloff that investors fear signals turmoil to come as financial markets adjust to a pullback in central-bank stimulus. -- The declines extend a dark beginning of the year for equity investors world-wide, a jarring drop for markets that climbed imperviously through 2013. -- The Dow Jones Industrial Average fell 318.24 points, or 2%, to 15879.11. The Stoxx Europe 600 lost 2.39%, and Germany's DAX, down 2.48%, had its sharpest fall in months. The Nikkei also fell 1.94%. -- While those drops were dramatic, much of the pain of investors' readjustment is landing on developing economies, from Brazil and India to Thailand and South Africa.