By Devik Jain and Noel Randewich (Reuters) – The S&P 500 ended lower after a volatile session on Monday, with investors wrestling with uncertainty and bank stocks dropping following powerful Western sanctions against Russia as it continued its invasion of Ukraine. Helping the Nasdaq close in positive territory after opening at a loss, electric car makers Tesla and Rivian Automotive jumped 7.5% and 6.5%, respectively. Citigroup fell 4.5% and helped push the S&P 500 banks index down 2.35% as the U.S. 10-year Treasury yield slipped. The broader S&P 500 financial index dropped 1.5%. Global stocks …