FX Swap Shock: Is Your EA Losing Money While You Sleep?
## What's the idea?
A beginner-friendly summary of the verification: “FX Swap Shock: Is Your EA Losing Money While You Sleep?”.
What’s the idea?
When we talk about taking an Expert Advisor (EA) from backtesting to live trading, it’s easy to focus just on the raw profit/loss numbers. But there are crucial “hidden” costs and benefits that can make or break a strategy in the real world. Today, we’re diving into one of those big ones: swap costs. What are swaps? In FX trading, a swap is basically the interest you either pay or receive for holding a position overnight. It’s determined by the interest rate differential between the two currencies in a pair. If you’re holding a currency with a higher interest rate against one with a lower rate, you might earn swap (a “positive carry”). If it’s the other way around, you’ll pay swap (a “negative carry”). For our particular EA, we found that trades are held for an average of 6.8 days. That’s long enough for swap costs and benefits to really add up and impact overall profitability. So, understanding them isn’t just an academic exercise – it’s vital for knowing what to expect when we go live.
How I tested it
To figure out the potential impact of swaps, I calculated the estimated swap cost/benefit using a simple formula: the notional value of the trade × holding days × daily swap rate for that specific asset.
“Notional value” just means the total value of the position. For instance, if you trade 1 lot of EUR/USD, the notional value is €100,000, even if you only put up a small margin.
I looked at the “notional-days” for different asset classes our EA trades. This gives us a sense of where the biggest exposure to swaps lies:
- JPY Crosses (like USD/JPY, EUR/JPY): 4213 notional-days (this was the biggest chunk!)
- Indices (like stock market indices): 1082 notional-days
- Gold: 895 notional-days
- Non-JPY FX (like EUR/USD, GBP/USD): 229 notional-days As you can see, JPY Crosses dominate the volume when it comes to positions held long enough for swaps to matter. This tells us that the interest rate dynamics around the Japanese Yen will have a huge influence on our swap costs.
What happened?
Here’s where it gets interesting! After running the numbers, I found that the swap impact isn’t always a fixed cost. It can actually be a benefit, a cost, or roughly neutral, depending on the market’s interest rate environment. I identified three main scenarios:
- Favorable Scenario (Current Regime): +0.18% per month
- In the current market environment, where interest rates in countries like the US are significantly higher than Japan’s (think USD > JPY interest rates), our EA actually benefits from swaps! This is because our largest open positions are typically long JPY Crosses. Being “long” a JPY cross means you’re buying the currency against JPY (e.g., buying USD and selling JPY in USD/JPY). Since the non-JPY currency often has a higher interest rate, we receive interest. This positive “carry” from our JPY Cross long positions is strong enough to offset any financial costs from holding Gold or Index positions.
- In other words: Swaps are currently a tailwind for this EA, adding about 0.18% to our monthly returns!
- Neutral Scenario: -0.04% per month
- In a more balanced interest rate environment, swaps would be a minor drag, costing only about 0.04% per month. This is very close to neutral, meaning they don’t significantly impact profitability either way.
- Unfavorable Scenario (JPY Carry Reversal): -0.30% per month
- This is the scenario we need to watch out for! If there’s a significant shift in global interest rates, particularly if the interest rate differential between JPY and other major currencies narrows or even reverses (a “JPY carry reversal”), then swaps could turn into a substantial monthly cost of -0.30%.
- In other words: Imagine if Japan’s interest rates suddenly rose, or other countries’ rates dropped. Our “long JPY Cross” positions might no longer earn positive swap, or could even start paying swap. This is what we call “carry compression,” and it would eat into our profits.
The Catch: Watch for Carry Reversal!
While the current environment offers a nice swap tailwind, the potential for a JPY carry reversal is a serious risk. It’s crucial to monitor global interest rate trends, especially those involving the Japanese Yen. A shift here could flip our swap benefit into a significant cost.
What I learned
So, where does this leave us for taking the EA live? This swap analysis (Research 107) combined with our previous work on spread and slippage costs (Research 106) gives us a much clearer picture of real-world profitability. Let’s sum up the total expected costs and benefits:
- Spread and Slippage (from Research 106): These typically cost us around -0.04% per month. During periods of higher volatility and market stress, they can add an extra 1.5-2% to drawdowns. (A “drawdown” is the peak-to-trough decline in your account balance.)
- Swaps (from this research, Research 107): These range from neutral to a beneficial +0.18% per month in the current market regime. Putting it all together, our live estimate for this EA’s performance:
- Expected Net Monthly Profit: Approximately 0.7-0.8% per month
- At an Estimated Drawdown: Around 10% In other words: When accounting for all these real-world trading costs and benefits, we can realistically expect this EA to generate around 0.7-0.8% profit per month, assuming a typical drawdown of about 10%. This isn’t a get-rich-quick number, but it’s a realistic and verifiable estimate. The key takeaway here is that while the current interest rate environment makes swaps a positive factor, we must remain vigilant. The moment we see signs of a JPY carry reversal, that +0.18% could quickly turn into a -0.30%, significantly impacting our net profitability. Continuous monitoring of macroeconomic conditions, especially interest rate differentials, will be essential for managing this EA in production.
How this connects
This verification builds on earlier ones (what failed before and what I tried this time, comparisons between approaches).