U.S. stocks close mostly lower Monday on heightened Ukraine worries

U.S. stock closed mostly lower Monday as investors weighed the latest sanctions against Russia after it attacked Ukraine and Russian President Vladimir Putin raised its nuclear alert level. The S&P 500 SPX, -0.24% ended about 0.3% lower, while the Dow Jones Industrial Average DJIA, -0.49% fell 0.5% and the Nasdaq Composite COMP, +0.41% gained 0.4%, according to preliminary FactSet data. The White House said over the weekend that the U.S. and its allies vowed to remove some Russian banks from the Society for Worldwide Interbank Financial Telecommunication, a messaging service that helps banks execute financial transactions.