South Korea's money supply remained unchanged in May compared with a month earlier amid an extended tightening policy mode, central bank data showed Monday.The country's M2, a key gauge of the money supply, stood at 4,014 trillion won (US$2.909 trillion) in May, flat from the previous month, according to the preliminary data from the Bank of Korea (BOK).The M2 is a measure of the money supply that counts cash, demand deposits and other easily convertible financial instruments.The central bank has been implementing a restrictive mode as it delivered seven consecutive hikes in borrowing costs from April 2022 to January 2023 to tame soaring inflation in Asia's fourth-largest economy.Early this month, the BOK held its key interest rate steady at 3.5 percent for the 12th straight time amid moderating inflation.Source: Yonhap News Agency