The Hong Kong Monetary Authority (HKMA) announced on Wednesday that the city\'s total assets of the Exchange Fund increased by 153.6 billion HK dollars to 2.6463 trillion HK dollars at the end of January, on December 2011. The Monetary Authority said that foreign-currency assets increased by 78.6 billion HK dollars and Hong Kong dollar assets increased by 75 billion HK dollars. The rise in foreign currency assets was mainly due to purchases of foreign currencies with HK dollars, valuation gains on foreign currency investments, increases in unsettled purchases of securities and Certificates of Indebtedness, said the HKMA. The Currency Board Account shows that the Monetary Base at the end of January was 1,091.2 billion HK dollars, up 15.2 billion HK dollars, or 1.4 percent, from the end of December 2011. The rise was mainly due to an increase in Certificates of Indebtedness. Backing Assets increased by 14.4 billion HK dollars, or 1.2 percent, to 1,186.4 billion HK dollars. At the end of January, the backing ratio decreased from 108.92 percent to 108.72 percent. (One U.S. dollar is equivalent to 7.76 HK dollars)