NEW YORK—U.S. stocks ended a choppy session lower on Monday as investors grew nervous ahead of third-quarter earnings reporting season. Supply chain problems and higher costs for energy and other things have fueled concern about earnings, set to kick off with JPMorgan Chase & Co. results on Wednesday. Indexes reversed early gains after midday and added to losses just before the close. JPMorgan shares were down 2.1 percent and among the biggest drags on the S&P 500 along with Amazon.com, which fell 1.3 percent. The S&P financial index was down 1 percent, while communication services dropped 1.5 percent. “The market is a bit cautious going into this earnings season,” said Tim Ghriskey, chief investment strategist at Inverness Counsel in New York. “Supply chain issues may have impacted earnings for a number of companies and certain industries more than others.” While another period of strong U.S. profit growth is forecast for …