The 9‑Step Backtesting Trap That Blew Up My Dhaka Fintech’s AML Engine
AI-generated illustration Bangladesh, 09/28/2026. My phone buzzed at 02:17 am. An alert from our real‑time MFS monitor flashed: BDT 3,245,876 moved across three Rocket accounts in 12 minutes, all under the BFIU’s BDT 100,000 threshold. My gut screamed – this was a structuring ring about to explode. I fired up the back‑testing suite we’d built two years ago, expecting a clean hit list. The report came back empty. Zero alerts. My heart sank. Two weeks later, the regulator knocked. A formal audit discovered that our back‑testing methodology was blind to exactly the pattern we’d just seen. The BFIU cited us for “inadequate validation of detection logic.” I was forced to shut down the alert engine for a week while we rewrote the whole thing. The Hidden Problem: Why Most Bangladeshi Backtests Miss the Real Threat Everyone tells you to “split your data 70/30, train on the past, test on the future.” Sounds neat. In reality, our local MFS landscape throws that rule out the window. Transaction ...