CNBC.com’s MacKenzie Sigalos brings you the day’s top business news headlines. After an ugly month for stocks in September, CNBC’s Bob Pisani breaks down what investors should expect in October, and identifies hurdles that lie ahead, like the presidential election and the rising Covid-19 case count. Plus, CNBC.com airline reporter Leslie Josephs returns to "After Hours" as American and United cut more than 30,000 jobs in one day after their federal aid funds ran dry….