The Dow Jones industrial average on Friday fell below 10,000 for the first time in two months—closing at 9,962, down almost 2 percent for the week—as concern mounted about slowing corporate-earnings growth. Investors sold stocks across all sectors and industries, with technology and consumer-products marketers taking the brunt of the sell-off. Coca-Cola was the latest company to issue disappointing second-quarter earnings and a cautious outlook for the rest of the year. It cited international businesses coming under increasing competitive pressure. Amazon also spooked investors, reporting sluggish sales. On the Big Board, Omnicom had a wild time, jumping above $71 a share before closing at $69.53, still up 1.5 percent for the week. IPG’s stock price was flat, closing at $12.77. WPP, trading as American Depository Receipts on the Nasdaq, fell 3 percent to $47.08.