[1/2] Traders work on the floor of the New York Stock Exchange (NYSE) in New York City, U.S., July 19, 2023. REUTERS/Brendan McDermid/File Photo Summary Companies July retail sales rise more than expected Nvidia gains as UBS, Wells Fargo raise PT U.S. big banks fall as a report warns of downgrades Indexes down: Dow 0.65%, S&P 0.60%, Nasdaq 0.47% Aug 15 (Reuters) – Wall Street's main indexes fell on Tuesday after stronger-than-expected retail sales data stoked worries interest rates could stay higher for longer, while U.S. big banks dropped on a report that Fitch could downgrade some lenders. The Commerce…