S&P 500 stumbles back into negative territory late 22-Sep-21 05:11 am AnalysisAnalysis, US Market Anirudh Sethi Closing changes for the main US equity boursesS&P 500 -3.5 points to 4354Nasdaq +0.4%DJIA -0.1%Toronto TSX composite +0.6%FedEx also reported earnings after the bell and shares quickly fell 2% on lower guidance.