Stock Market Today: S&P 500 and Nasdaq are up in tech-fueled rally as Nvidia's stock jumps after its earnings beat expectations; Dow rises as Salesforce shares surge and Jackson Hole symposium gets started; Marvell Technology results on tap

The S&P 500, Nasdaq and Dow were rising Thursday afternoon as tech rallied after earnings reports from Nvidia and Salesforce. Traders also were assessing the latest weekly jobless claims data while looking ahead to Fed…