US President Barack Obama warned Wall Street Wednesday that it should be \"concerned\" about the escalating fiscal and political crisis that has shut down the US government. Obama spoke in an interview with CNBC broadcast immediately after US markets closed, and after meeting top CEOs of Wall Street financial firms at the White House as a fight over raising the US debt ceiling coincides with the government shut down. \"This time\'s different. I think they should be concerned,\" Obama said, when asked whether the Washington crisis was just the latest of a series of political rows that would quickly blow over. \"Democracy\'s messy. But when you have a situation in which a faction is willing potentially to default on US government obligations, then we are in trouble,\" Obama said.