U.S. stock markets will not open on Monday and possibly Tuesday, NYSE Euronext said in a statement late Sunday. Previously the New York Stock Exchange had planned to close the physical floor but electronic trading would remain open. NYSE's statement: "In consultation with other exchanges and market participants, NYSE Euronext (NYX) will close its markets on Monday, Oct. 29, 2012 and pending confirmation on Tuesday, Oct. 30, 2012. We support the