NEW YORK (TheStreet) -- Shares of Citigroup Inc.a aare up 0.66% to $50.40 after the bank bought Deutsche Bank AG's energy and metals book, in the latest sign of expansion from the U.S. firm in commodities trading, Reuters reports. The deal will help Citi compete with top banking rivals in commodities trading, Reutersaadded,aeven as some exit the sector under increased regulatory scrutiny and lower margins.