U.S. stock index futures fell ahead of key inflation data and the first presidential debate between Vice President Kamala Harris and former President Donald Trump, with analysts suggesting Harris performed better, shifting betting odds in her favor. The S&P 500 and Nasdaq futures experienced slight declines of 0.4% and 0.5%, respectively, while the dollar also weakened. Investors are closely monitoring August's consumer price inflation, expected to show a year-on-year rate of 2.6%, as this could influence the Federal Reserve's interest rate decisions next week. Despite the debate and inflation data, market sentiments remained mixed, with traditional safe-haven assets gaining and Treasury yields dropping. Overall, while some analysts are optimistic about potential interest rate cuts, uncertainty surrounding economic policies post-election continues to weigh on investor confidence.