金管局半年内双向干预，是何缘故？

Core Viewpoint - The Hong Kong Monetary Authority (HKMA) intervened in the currency market on June 26, 2023, selling USD and buying HKD to maintain the peg of the Hong Kong dollar to the US dollar, marking the first intervention since May 2023 [2][8]. Group 1: Currency Peg Mechanism - The Hong Kong dollar has been pegged to the US dollar since October 17, 1983, maintaining a stable exchange rate between 7.75 and 7.85 HKD per USD through a currency board system [3]. - The mechanism relies on 100% USD asset backing, meaning for every HKD issued, the HKMA must hold an equivalent of 0.127-0.129 USD in foreign reserves [3][4]. - The issuance and redemption of HKD are linked to the deposits and withdrawals of USD by commercial banks, ensuring that changes in USD assets directly affect the HKD monetary base [4]. Group 2: Maintaining Exchange Rate Stability - The HKMA employs an automatic interest rate adjustment mechanism and official interventions to stabilize the HKD exchange rate [5]. - Market forces determine the exchange rate within the 7.75-7.85 range, with arbitrage activities helping to keep the HKD stable [5][6]. - The HKMA intervenes only when the exchange rate hits the extremes of 7.75 or 7.85, avoiding excessive market distortion while maintaining credibility against speculative attacks [6]. Group 3: Recent Market Dynamics - The recent triggering of the weak-side convertibility guarantee was influenced by unexpected US policies under Trump, leading to a depreciation of the USD and a shift of funds towards emerging markets, including Hong Kong [8]. - The Hong Kong stock market saw a significant increase in daily trading volume, averaging over 200 billion HKD since February 2023, indicating a surge in market liquidity [10]. - The revival of IPO activities in Hong Kong has attracted substantial interest from investors, with several high-profile listings contributing to increased demand for HKD [12]. Group 4: Impact of Previous Interventions - In May 2023, the HKD strengthened to 7.75, prompting the HKMA to buy USD and sell 1,294 billion HKD, resulting in a significant increase in the banking system's HKD surplus [13]. - The interbank borrowing rate (HIBOR) dropped sharply from 4.20% to 0.59% due to increased liquidity, leading to a widening interest rate differential between HKD and USD [13][15]. - Recent arbitrage activities have increased the supply of HKD in the market, putting downward pressure on the HKD/USD exchange rate, which led to the recent intervention by the HKMA [15].