You’ve built the perfect EA. It crushes backtests, dominates demo accounts, and then… flops on live. What gives? Is your broker sabotaging you? Is your EA haunted? Not quite. Let’s break down the real reasons your Expert Advisor might act like a model citizen in demo but turn into a rebel in live trading.
🧪 1. Liquidity: The Demo Illusion
Demo accounts simulate ideal conditions. Every order gets filled instantly, no slippage, no partial fills, no liquidity gaps. But in live markets, you're competing with real traders for real liquidity. That means:
- Slippage happens—especially during news or low-volume hours.
- Partial fills can occur if your order size is too big for the available liquidity.
- Requotes and delays are real, especially with market execution.
Your EA might assume it always gets filled at the requested price. In live trading, that assumption can break your logic.
🧠 2. Execution Speed: Milliseconds Matter
In demo, execution is lightning-fast. On live, your order has to travel through your broker’s servers, possibly get routed to a liquidity provider, and then back. That delay—often just milliseconds—can:
- Cause missed entries or exits
- Trigger stop losses prematurely
- Affect scalping and high-frequency strategies the most
If your EA relies on ultra-precise timing, even tiny delays can throw it off.
🧾 3. Spread & Commission Differences
Demo spreads are often fixed or artificially tight. Live spreads? They widen during volatility, news events, or low liquidity. Add commissions, and your EA’s profit margin shrinks.
- Scalpers beware: A 1-pip spread on demo might become 3 pips live.
- Break-even trades on demo can become losers live.
Always test your EA with realistic spread and commission settings.
🧯 4. Psychological Pressure (Yes, It Affects You Too)
Even if your EA is fully automated, you’re still the human behind the screen. On demo, you let it run. On live, you might:
- Close trades early
- Disable the EA mid-trade
- Tweak settings impulsively
Fear and greed don’t disappear just because you’re using an algorithm. They just wear a different hat.
🧩 5. Broker Differences & Account Types
Not all brokers treat demo and live accounts equally. Some differences include:
- Server location (affecting latency)
- Order routing (A-book vs B-book)
- Execution model (market vs instant)
Even switching from a cent account to a standard account can change how your EA performs.
🧪 So What Can You Do?
- Forward test on a live micro or cent account before going big.
- Use realistic modeling in backtests (variable spreads, slippage, commissions).
- Avoid over-optimization—curve-fitting to demo data won’t help live.
- Log everything—track slippage, execution time, and trade outcomes.
- Stay calm—trust your system or improve it, but don’t panic.