The Hong Kong Monetary Authority on Wednesday injected 4.65 billion HK dollars into the market to prevent the value of the Hong Kong dollar from rising too much. The move came as the local currency hit 7.75 dollars to the U.S. dollar -- the stronger end of the trading range allowed under the exchange rate mechanism. The buying of U.S. dollars is triggered automatically when the exchange rate hits the upper limit of the trading band under the Currency Board Mechanism. Following the move, the total balances on clearing accounts maintained by banks with the authority will reach 225 billion HK dollars on Friday. This is the 21st time the authority injected money into the market to keep the exchange rate stable since Oct. 20, 2012, and the total amount has exceeded 76 billion HK dollars.