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When equity volatility spikes, as shown by the VIX, currency spreads typically widen. Liquidity providers raise their prices for risk, and the cost of trading goes up just when moves get larger.

The relationship is nearly mechanical. Quote engines use volatility estimates to set spreads. A rise in realized or implied volatility feeds into the formula, and the spreads follow.

For scalpers, the result is a squeeze from two sides: more movement, which looks like opportunity, and more cost, which eats the profits. The net effect depends on whether the extra movement outweighs the extra spread.

Evidence from broker data suggests that for typical retail strategies, high-volatility periods are worse in net terms than moderate ones. The spread cost rises faster than the average edge.

A useful approach is to define regimes by spread rather than by chart appearance. If the spread is more than twice the daily average, treat it as a different market, with different expectations or no trading at all.

Tracking the average spread for each hour and a rolling comparison of the current spread to that average is easy to build into a simple indicator.

What multiple of the normal spread has been the threshold for stepping aside?

I settled on twice the normal spread as my line after a rough week during a volatility spike a while back. Everything was moving, and my charts were full of setups, but my fills were consistently worse and my targets were being eaten by the cost of getting in and out. I finished that week down despite feeling like I'd read the market well.

Afterwards I built a simple indicator that shows the current spread next to the average for that hour of the day over the past month. It turned out that my worst days lined up with the spread running well above that average, much more than with any chart pattern or news event.

Now when the spread is above about twice the hourly average I simply don't trade, and between one and a half and two times I cut size and widen targets. It feels like giving up opportunity when the screen is busy, but the numbers say I keep more by staying out.