___Herbalife stock surges after Icahn grabs stake NEW YORK (AP) â¿¿ Strictly business, nothing personal. That's how Carl Icahn characterizes the latest turn in his clash with fellow Wall Street titan William Ackman. Both men have a keen interest in Herbalife, a maker of dietary supplements designed to promote weight loss. Ackman claims the company is a fraud and has bet that its stock price will crumble; Icahn says it's a great buy. They both can't be right, and for now it's not clear which one is. Icahn, for his part, disclosed in a regulatory filing late Thursday that he had taken a 13 percent stake in the company, essentially betting that Ackman is dead wrong. Icahn says he's not making his bet merely to spite Ackman. ___ US factory output falls on weak auto production WASHINGTON (AP) â¿¿ U.S. factories slowed production in January after two solid months of cranking out goods. The weakness mainly reflected a big drop in output at auto factories that is likely temporary. Manufacturing output fell 0.4 percent in January from December, the Federal Reserve said Friday. The decline followed increases of 1.1 percent in December and 1.7 percent in November. Overall industrial production edged down 0.1 percent in January compared with December. Output In mining, the category that covers oil and gas drilling, fell 1 percent. Utility output jumped 3.5 percent, as a cold snap led more households to turn up their heat. ___ Foreign holdings of US debt hit $5.56 trillion in December WASHINGTON (AP) â¿¿ Foreign demand for U.S. Treasury securities rose to a record level in December, evidence that overseas investors remained confident in U.S. debt despite on-going budget battles in Washington. The Treasury Department said Friday that foreign holdings of U.S. Treasurys rose 0.3 percent in December from November to $5.56 trillion. It was the 12th consecutive monthly gain.