U.S. stocks ended lower on Monday as heightened fears over Middle East instability, following Iranian missile strikes and a maritime explosion, spooked investors. The Dow Jones Industrial Average and the S&P 500 both fell, with losses in ten out of eleven sectors, while energy stocks gained as oil prices surged to $106.42 per barrel. Earnings reports added to the volatility, with significant drops in shares of FedEx and Norwegian Cruise Line, contrasting with gains for some companies like Tyson Foods.