The Round Number and Penny Stop Effect in the Foreign Exchange Market

The Round Number and Penny Stop Effect in the Foreign Exchange Market

It's important for brokers and analytical platforms to disclose the mechanics of liquidity formation, not just chart patterns.
Millions of orders intersect every second on the forex market. But even in this apparent chaos, patterns can be discerned—for example, the special power of "round numbers ." Levels like 1.2000 for EUR/USD or 150.00 for USD/JPY attract attention like a magnet. Why? Because they are psychologically significant.

This peculiarity of human perception shapes behavioral patterns skillfully exploited by both professional traders and market makers. Together with the phenomenon of "penny stops" (stop-hunting at nearby levels), these effects create a market microstructure where the struggle between liquidity and emotion becomes visible.

The Round Number and Penny Stop Effect in the Foreign Exchange Market

What is the round number effect?

It's long been known in decision psychology that people find it easier to remember and manipulate whole numbers. In financial markets, this manifests itself in the concentration of orders at zero-based levels—1.1000, 0.8500, 150.00, and so on.

For example, a 2024 study by the Bank for International Settlements (BIS) found that up to 22% of all limit orders on currency pairs are located near round levels.

When the price approaches these points, a surge in volume and volatility occurs. For HFT algorithms and institutional players, this is a signal: at these points, liquidity can be extracted and a short-term move can be triggered.

Penny Stops: The Hunt for Liquidity

The "penny stops" phenomenon is due to the fact that retail traders often set stop-losses too close - literally "a few points" from the round level.

Example: If the EUR/USD price is hovering around 1.2000, most retail participants' stops will be between 1.1990 and 1.1995. Large players know this and "break" these zones to gather liquidity. After a short downward impulse, the price often rebounds sharply—a so-called "fake breakout . "

For institutions, this is a common practice—not malicious, but part of the market's search for liquidity. For traders, it's a reason to be cautious: don't set stops in plain sight.

Why does this work?

Crowd psychology. Round numbers act as a guide: "If EUR/USD reaches 1.1000, I'll buy." This is the predictability that algorithms exploit.

Order consistency. Automated trading systems (including MetaTrader expert advisors) often use these levels by default.

Liquidity compression. Pending orders accumulate near round numbers, and the slightest imbalance instantly causes a price surge.

"Psychological levels aren't just numbers. They're the points where the expectations and strategies of thousands of participants intersect," notes FX24 Research analyst Marai Vlasova.

How to use the effect in trading

Place orders slightly above/below the round levels.
For example, instead of 1.2000, place orders at 1.2003 or 1.1997.

Analyze the price action after the breakout. If the momentum quickly fades, it was likely a stop-loss attempt.

Combine with volume analysis. Peaks and volume spikes near round levels signal a potential reversal.

Use liquidity indicators. Some brokers and platforms (including MetaTrader 5 and cTrader) allow you to monitor order concentration.

GEO and its impact on global markets

The round number effect is most pronounced in the USD/JPY, EUR/USD, and GBP/USD pairs—these pairs account for over 65% of global currency turnover (according to BIS data). The impact of penny stops is especially noticeable during the Asian session, when liquidity is lower and small orders can trigger significant movements.
American and European HFT firms (Virtu Financial, Citadel Securities) are actively using machine learning models to predict these points of liquidity concentration.


The "round number" effect and the "penny stop" phenomenon are not random, but a reflection of crowd psychology and the logic of liquidity. Ignoring these zones is betting against the odds.

For a trader, knowing these patterns is not a tool for guessing, but for adaptation: where to enter, where to exit, and where not to place a stop. In the volatile market conditions of 2025, these details could become your competitive advantage.
Written by Ethan Blake
Independent researcher, fintech consultant, and market analyst.
November 10, 2025

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