The weekend gap — what your stop can't save you from

Your stop-loss is a promise from the market that it does not sign. In normal conditions it holds — price touches the level, the order fills, the damage matches the plan. Then comes Sunday evening: the market opens 40 pips away from Friday's close, and the stop "at 1.0850" fills at 1.0812. That is a gap, and it is the one routine event that breaks the per-trade risk math.

Why gaps happen

Markets close; the world doesn't. Over the weekend, rate decisions, election results, crisis headlines, and Monday's Asia open reprice everything at once. When trading resumes, the first print is wherever the new consensus is — not where Friday's chart ended. Your stop lives in the space between those two prices, and market orders fill at the first available price. The gap risk is largest in: JPY pairs (weekend policy surprises), gold (geopolitical headlines), and thin exotic crosses; smallest in the most liquid majors — but "smallest" is not "none."

What it does to the risk math

Position sizing assumes the stop caps the loss: risk = stop distance × pip value × lots. A gap invalidates the "caps" part — the real loss can be 1.5×, 2×, more in a crisis Monday. The practical translation: the size you carry into the weekend should assume a worse fill than the stop promises. If 1% risk at the planned stop becomes 2% in a gap, either halve the size before the close or accept the doubled risk knowingly. The position size calculator does the arithmetic; the decision to run weekend risk is yours.

Three honest policies

1. Close before Friday's close. The purist's choice — zero gap exposure, zero weekend stress. Costs swap avoidance and the chance of a gap in your favor (which is not a reason; lotteries have favorable outcomes too).

2. Hold with reduced size. Halve (or third) the position over the weekend so a 2R gap loss equals a normal 1R week. This is the professional compromise.

3. Hold full size and write the check. Acceptable only when the account can absorb a multi-R loss without a plan change — and when the trade's thesis genuinely runs on multi-day logic.

The rule that makes the choice safe

Whatever the policy, it must be a policy — the same rule every Friday, written in the plan next to the risk percentage. The account-killers aren't gaps; they are gaps taken on positions sized by Friday-evening optimism. Gap risk can't be eliminated. It can only be budgeted. Budget it.