When exactly do spreads start widening before a big release?

[Shadow Trader]

Not at the release. Earlier. Spread logs on a major pair show the widening beginning anywhere from one to five minutes ahead of a high-impact event, with most of the change in the last thirty seconds.

Liquidity providers withdraw size first, then widen. The platform's displayed spread may lag behind that, so the executable depth is already thinner than the quote suggests.

That timeline has a practical consequence for scalpers. A position opened at -2 minutes can be perfectly fine at the entry and then get closed at an exit that's three times as costly. Positions opened and closed entirely inside the pre-release window pay a bigger toll than they expected.

The exact pattern differs by event. Employment data and central bank decisions show the strongest effect. Mid-level data barely registers on some pairs.

Logging spread each second around ten releases on the pair of choice gives a plain picture. After a handful of events, the timing becomes predictable enough to set a "no new trades" cutoff based on evidence rather than guesswork.

When does the spread begin to widen on the pair traded before payrolls?