Right before London opens, the market starts to wake up. Early quotes widen, and the first few minutes of real volume often push price in one direction, only for that move to reverse once the main flow shows up.
Call it a fake-out, a stop run, or just positioning. Whatever the label, it happens often enough on EURUSD and GBPUSD that a pattern shows up: the first impulse after the bell is frequently the wrong one.
The reason isn't mysterious. Early movers are traders and dealers sizing up the overnight range. They test the highs and lows, trigger stops, and then the real orders arrive from participants who had no interest in chasing.
For a scalper, this can mean two things. Either sit out the first five to ten minutes entirely, or trade the reversal after the sweep. The second option sounds smarter and loses more money, because the sweep sometimes just keeps going and becomes the day's trend.
What's worth tracking is how far the first sweep usually goes relative to the Asian range. If it routinely extends 30 to 40 percent beyond the range before reversing, that gives a rough yardstick for sanity checks.
Is the London open sweep consistent enough to trade, or does it change character every week?