By Devik Jain and Noel Randewich Feb 28 (Reuters) - Wall Street tumbled in volatile trading on Monday, with investors wrestling with uncertainty and bank stocks dropping following powerful Western sanctions against Russia as it continued its invasion of Ukraine. Russian artillery bombarded residential districts of Ukraine's second-largest city, as Moscow's invading forces met stiff resistance on a fifth day of conflict. The worsening geopolitical crisis has added to investors' concerns about soaring inflation and the Federal Reserve's rate-hike plans, putting the three major U.S. stock indexes on track for their second straight month of losses.