Carry Trade Calculator
From principal, rates and FX change, compute the net return of a carry trade: borrow low, invest high, minus currency movement.
輸入資料
計算結果
重點速覽：A carry trade borrows in a low-rate currency to invest in a higher-yield one, earning the rate gap. net return = principal x (invest rate - borrow rate) + principal x FX change %. Example: borrow 1%, invest 5% (4% gap = HK$4,000 on 100k), but the invested currency falls 3% (-HK$3,000) → net HK$1,000 (1%). FX can add to or erase the carry. WARNING: FX risk is the main danger; a sharp adverse move can cause a loss bigger than the interest gain. In Hong Kong, HKD-USD is effectively pegged via the Linked Exchange Rate (≈7.75-7.85), so HKD-USD carry is almost FX-free; HKD vs other currencies still carries FX risk. Education, not advice.
計算公式
淨收益 = 本金 ×[(投資利率 − 借款利率) + 匯率變動] ÷ 100。
利差 =(投資利率 − 借款利率)；匯率變動為投資貨幣的升/貶值幅度。
$$淨收益：$Net = P \times \dfrac{(r_{invest}-r_{borrow})+\Delta_{fx}}{100}$$$$$其中 $P$ 為本金、$r_{invest}$ 與 $r_{borrow}$ 為投資 / 借款貨幣年利率、$\Delta_{fx}$ 為期間匯率變動 (%)。$$$$利差 (carry)：$r_{invest}-r_{borrow}$$$$$示例：$100{,}000 \times \dfrac{(5-1)+0}{100}=4{,}000$$$使用說明
- Enter the principal.
- Enter the invest (higher) and borrow (lower) rates.
- Enter the expected FX change %.
- View the net return.
本金 HK$100,000、利差 4% (投資 5% − 借款 1%) 下匯率變動對淨收益的影響
| 期間匯率變動 | 計算式 | 淨收益 (HK$) | 淨報酬率 |
|---|---|---|---|
| +2% (升值) | 100,000 × (4 + 2) ÷ 100 | 6,000 | 6% |
| 0% (不變) | 100,000 × (4 + 0) ÷ 100 | 4,000 | 4% |
| −2% (貶值) | 100,000 × (4 − 2) ÷ 100 | 2,000 | 2% |
| −4% (貶值) | 100,000 × (4 − 4) ÷ 100 | 0 | 0% |
理財情境案例
案例一：匯率穩定時的理想情境
投資者以 HK$100,000 執行利差交易：借入年息 1% 的低息貨幣，投入年息 5% 的高息貨幣，利差為 4%。假設期間匯率完全不變 (匯率變動 0%)。
淨收益 = 100,000 × [(5 − 1) + 0] ÷ 100 = 100,000 × 4 ÷ 100 = HK$4,000，即賺取 4% 的利差。
解讀：在匯率穩定、市場平靜的時期，利差交易確實能穩定地『收割』兩種貨幣的利率差。這也是它在低波動環境特別受歡迎的原因。但這個理想結果完全依賴『匯率不變』這個前提——一旦前提被打破，結果可能天差地遠。
案例二：高息貨幣貶值如何吞噬收益
同樣是 HK$100,000、利差 4% 的部位，但這次期間投資 (高息) 貨幣貶值了。分兩種情況比較：貶值 2% 與貶值 4%。
貶值 2%:淨收益 = 100,000 × [(5 − 1) − 2] ÷ 100 = 100,000 × 2 ÷ 100 = HK$2,000，收益減半。貶值 4%:淨收益 = 100,000 × [(5 − 1) − 4] ÷ 100 = 100,000 × 0 ÷ 100 = HK$0，利差被完全抵銷。
解讀：只要高息貨幣貶值幅度達到利差 (4%)，辛苦賺來的利差就全數化為烏有；再貶下去就開始蝕本金。歷史上多次 carry trade『平倉潮』都伴隨高息貨幣急貶，加上普遍使用槓桿，虧損被成倍放大。這說明利差交易的最大敵人是匯率風險，絕非穩賺策略。本工具僅供教學與估算，不構成投資建議。
常見問題
How exactly is the net return calculated?
Net return = principal x (invest rate - borrow rate) + principal x FX change %. The first term is the interest differential (carry) you earn; the second is the currency gain/loss. In the example (100k, 1% borrow, 5% invest, -3% FX): interest = 100k x 4% = 4,000; FX = 100k x -3% = -3,000; net = 1,000 (1%). A positive FX move would add on top of the carry.
Why is FX the main risk?
The interest gap is small and stable; currency moves can be large and sudden. A few per cent adverse FX move can erase the whole carry or turn it negative — especially in a risk-off event where high-yield currencies often fall most. The trade 'pays a small coupon but risks a large capital loss'; size positions for that asymmetry.
How does this relate to Hong Kong and HKD?
Hong Kong uses the Linked Exchange Rate System: the HKMA keeps USD/HKD within about 7.75-7.85 by virtue of the Currency Board. So a carry between HKD and USD is almost FX-risk-free (only the tiny band), and the rate gap is essentially the US-HK short-end difference. But HKD vs JPY, AUD, RMB or emerging-market currencies still carries real FX risk. Locally, many HK investors do USD/HKD deposits carry; cross-currency carry needs FX hedging awareness.
Is a higher carry always better?
Not necessarily. A very wide rate gap usually signals a currency the market expects to depreciate (the gap compensates for the FX risk). Chasing the highest carry without FX hedging can be the classic 'picking up pennies in front of a steamroller'. Judge the carry together with expected volatility and your hedge.
How do I control carry-trade risk?
Set position size for the worst-case FX move, use stop-losses or FX hedges (forwards/options), diversify across currencies, and avoid over-leverage. In HK, watch the HKMA's Convertibility Undertakings and the strong/weak sides of the band for USD/HKD. Educate yourself via the HKMA and IFEC before trading; this tool estimates only, not advice.
相關工具
參考資料
內容審核：香港計算器財經團隊。計算邏輯與公式參考香港金融管理局（HKMA）及投資者及理財教育委員會（IFEC）之個人理財計算指引，結果僅供參考，實際以相關機構公佈為準。