Weekly gap fills: easy money or a popular myth?

[Shadow Trader]

The saying goes that gaps always fill. In forex, weekend gaps in major pairs are usually small, a few pips to maybe 20, and many fill within hours or days. That stat gets quoted as if it guarantees profit.

The reality is more subtle. Gaps fill often because they are small, and small gaps are easy to fill. Bigger gaps, usually caused by real news over the weekend, can take weeks or never fill at all. A strategy that fades every gap works until the one that doesn't, and that one tends to be large.

For a scalper, there's a second problem: the spread at the open. A 6 pip gap with a 4 pip spread offers less than it appears to, and the stop needs room above the spread.

A more careful approach is to filter gaps by size and cause. Small gaps with no news background are candidates. Large gaps with a clear reason are best left alone.

How have gap trades performed in the journal, and has size made a visible difference?