港元與美元掛抅問題

HKD and USD exchange peg is not totally fixed. It is ranged between 7.75 and 7.85. Market participant can freely trade within this range. But when the market rate reaches either side of the boundary, the HKMA will intervene and guaranteed to buy USD at 7.75 or sell USD at 7.85 to maintain the exchange rate peg. That's why you will see the exchange is not the same every moment, but will stuck between the range.

對換率根據供求而定.多人買港元,就港元升.
但聯繫匯係金管局(好似係)用1:7.8的價錢購買港元或美元.投資者就在毫無風險的情況下取得利潤,稱為套戥.
但由於交易的過程中涉及交易成本,所以匯率在1:7.8 左右.