Gold futures ended lower on Tuesday, giving up earlier gains, as comments from Federal Reserve Chairman Jerome Powell suggested that the central bank might speed up tapering its monthly asset purchases when it meets next month. Prices for the metal shook off earlier gains that came after Moderna's /zigman2/quotes/205619834/composite MRNA -1.76% CEO Stéphane Bancel predicted that current vaccines would struggle against the omicron variant of the coronavirus. Comments from Powell, as well as Bancel, prompted steep declines in U.S. benchmark stock indexes, likely prompting investors to sell gold to cover margin calls. February gold fell $8.70, or 0.5%, to settle at $1,776.50 an ounce. Based on the most-active contract, prices ended the month down 0.4%, according Dow Jones Market Data.