International Monetary Fund Managing Director Christine Lagarde said Thursday that a failure to raise the U.S. debt ceiling could "very seriously damage" the global economy. "The government shutdown is bad enough, but failure to raise the debt ceiling would be far worse, and could very seriously damage not only the U.S. economy, but the entire global economy," Lagarde said in a speech at George Washington University ahead of the 2013 World Bank-IMF Annual Meetings. "So it is 'mission-critical' that this be resolved as soon as possible," she added. Referring to the anticipated tapering of Federal Reserve's quantitative easing program, Lagarde...