8 0 , ▁the ▁banks ▁will ▁convert ▁US ▁dollars ▁for ▁Hong ▁Kong ▁dollars ▁from ▁the ▁H K MA ; ▁Hong ▁Kong ▁doll ar ▁supply ▁will ▁increase , ▁and ▁the ▁market ▁rate ▁will ▁clim b ▁back ▁to ▁ 7 . 8 0 . ▁The ▁same ▁mechanism ▁also ▁works ▁when ▁the ▁market ▁rate ▁is ▁above ▁ 7 . 8 0 , ▁and ▁the ▁banks ▁will ▁convert ▁Hong ▁Kong ▁dollars ▁for ▁US ▁dollars . ▁ ▁The ▁Hong ▁Kong ▁doll ar ▁is ▁back ed ▁by ▁one ▁of ▁the ▁world ' s ▁largest ▁foreign ▁exchange ▁res erves , ▁which ▁is ▁over ▁ 7 ▁times ▁the ▁amount ▁of ▁money ▁supplied ▁in ▁circul ation ▁or ▁about ▁ 4 8 % ▁of ▁Hong ▁Kong ▁dollars ▁M 3 ▁at ▁the ▁end ▁of ▁April ▁ 2 0 1 6 . ▁ ▁Str ength ening ▁of ▁C urrency ▁Board ▁Arr ang ements ▁ ▁Since ▁ 5 ▁September ▁ 1 9 9 8 , ▁the ▁H K MA ▁has ▁provided ▁a ▁explicit ▁convert ibility ▁undert aking ▁to ▁all ▁lic ensed ▁banks ▁in ▁Hong ▁Kong ▁to ▁convert ▁Hong ▁Kong ▁dollars ▁in ▁their ▁clear ing ▁accounts ▁into ▁US ▁dollars ▁at ▁the ▁fixed ▁exchange ▁rate ▁of ▁H K $ 7 . 7 5 ▁to ▁US $ 1 . ▁Starting ▁from ▁ 1 ▁April ▁ 1 9 9 9 , ▁the ▁convert ibility ▁rate ▁in ▁respect ▁of ▁the ▁A ggreg ate ▁Bal ance ▁moved ▁from ▁ 7 . 7 5 ▁by ▁ 1 ▁pip ▁( i . e . ▁$ 0 . 0 0 0 1 ) ▁per ▁calendar