The Exotic Data ProblemIf you have built a backtesting pipeline for $EUR/USD or $GBP/USD and tried to run it on $USD/ZAR, you have probably

The Exotic Data ProblemIf you have built a backtesting pipeline for $EUR/USD or $GBP/USD and tried to run it on $USD/ZAR, you have probably noticed something is off. Your fill assumptions are wrong. Your spread model is wrong. Your slippage estimates are off by an order of magnitude. As of June 2026, exotic pairs continue to challenge traders who assume all forex data is created equal.The problem is not that exotic pairs are unbacktestable. The problem is that most backtesting frameworks make implicit assumptions that break down when liquidity thins. Here is a practical guide to fixing those assumptions in...