Market Structure in Forex: BOS and CHoCH Explained

BOS, CHoCH, internal, external: the vocabulary of market structure in forex can make a simple idea sound like a private code. Underneath the labels is the oldest question in chart reading, which is whether price is still making higher highs and higher lows.

Quick answer: Market structure in forex is the sequence of swing highs and swing lows on a chart. Higher highs and higher lows describe an uptrend; lower highs and lower lows a downtrend. A break of structure (BOS) is a close beyond the last swing in the trend’s direction. A change of character (CHoCH) is the first close beyond the last swing against it.

What is market structure in forex?

Market structure is a way of describing a chart by its turning points rather than by its indicators. Every time price rises and then pulls back, it leaves a peak, a swing high. Every time it falls and then bounces, it leaves a trough, a swing low. Join them up and the chart becomes a zigzag, and the zigzag has only three basic shapes:

• Uptrend: each swing high is higher than the last (a higher high, HH), and each swing low is higher than the last (a higher low, HL).
• Downtrend: lower highs (LH) and lower lows (LL).
• Range: highs and lows roughly level, with no clear sequence in either direction.

None of this is new. Charles Dow described trends in exactly these terms in his newspaper editorials around 1900, and the higher-high, higher-low definition is the standard one in classic technical analysis; our guide to how to identify a trend covers it with examples. What the modern “smart money” vocabulary adds is a set of names for the moments when the sequence continues or breaks: BOS and CHoCH.

Those names are useful shorthand. They are also descriptions of price drawn after the swings have formed. A break of structure tells you what price has done. It does not tell you who did it or what happens next, and it is no evidence of bank activity, however often it is presented that way.

Defining swing highs and swing lows with one rule

Before you can say a high is “higher”, you need to agree what counts as a high at all. This is where most of the disagreement between teachers starts, and it is worth settling before anything else.

A common, checkable rule is the N-candle rule: a candle is a swing high if its high is higher than the highs of the N candles on each side of it. With N = 2, that is the five-candle pattern known on many platforms as a fractal. A swing low is the mirror image: a low lower than the lows of the N candles on each side.

The rule has a built-in delay. With N = 2 you cannot confirm a swing high until two candles after it have closed, so on a four-hour chart the swing is eight hours old by the time you can label it. A larger N gives fewer, more significant swings but a longer delay. A smaller N reacts faster but labels every wiggle as a swing.

Other teachers use different definitions: a pullback of at least a set number of pips, a retracement of a set share of the previous leg, or a close (rather than a wick) beyond the previous candle. Some draw swings “by eye”, which cannot be tested at all. Any of the checkable versions can work as a description. The point is that different rules produce different structures from the same prices, and therefore different BOS and CHoCH signals.

Pick one rule, write it in your plan and apply it the same way on every chart. A second consistency issue is the price feed itself. Forex trades over the counter, between banks, brokers and platforms, rather than on one exchange: the BIS Triennial Survey put turnover at $9.6 trillion a day in April 2025, spread across many venues. Two platforms’ candles can differ by a pip or two at the extremes, so a swing high on one chart may be a pip short of a break on another. A rule that depends on a single pip is fragile. The Academy lesson on swing highs and swing lows practises the rule on real-looking charts.

Break of structure (BOS): when the trend continues

A break of structure (BOS) happens when price moves beyond the last swing point in the direction of the trend. In an uptrend, a BOS is a break above the most recent swing high. In a downtrend, a break below the most recent swing low. It confirms that the sequence of higher highs, or lower lows, is still going.

Two rules have to be settled here as well:

1. Close or wick? Some traders count any trade beyond the swing, even a wick. Others require a candle to close beyond it. The close rule produces fewer false breaks but reacts later.
2. Which timeframe? A BOS on the 15-minute chart may be a small wiggle inside a four-hour pullback. Always say which chart a structure label belongs to.

The left-hand candle in that figure is the shape that “liquidity” teachers call a sweep: price trades through an obvious high, triggers the buy stops resting above it, and falls back. Our guide to liquidity sweeps and stop hunts looks at why that happens and what the evidence on stop orders says.

Step through the chart below to follow an uptrend through two breaks of structure and then a change of character. It uses the two-candle swing rule and a close rule for breaks.

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Illustrative EUR/USD 4-hour chart, two-candle swing rule, close rule for breaks. Two breaks of structure confirm the uptrend; then a close below the last higher low is the first change of character.

Change of character (CHoCH): the first break against the trend

A change of character (CHoCH) is the first time price breaks the last swing point against the trend. In an uptrend, that means a close below the most recent higher low. In a downtrend, a close above the most recent lower high. The term borrows the idea of a market’s “character” changing from steady higher lows to something else.

In classic terms, a CHoCH is the first lower low after a run of higher lows, and it often comes after a failure swing: a rally that does not make a new high. Dow-style analysts said a trend remains in force until there is a definite signal that it has reversed, and a single CHoCH is a weak signal on its own. Common variations include:

• CHoCH then BOS: treat the CHoCH as a warning and wait for the opposite sequence to confirm, for example a lower high followed by a bearish break of structure.
• CHoCH on a lower timeframe: use a CHoCH on the hourly chart as a timing signal inside a four-hour pullback, in the direction of the four-hour trend.
• Some teachers call any break of the swing that started the last BOS a CHoCH, while others use the most recent swing. These pick different levels, so they disagree about when the character changed.

Every one of these is a rule about labels. None of them changes what the prices did. The next section shows how the same chart can carry two sets of labels at once.

Internal and external structure

Prices make swings within swings. External structure is the larger sequence that defines the trend on your chosen timeframe: the major swing highs and lows. Internal structure is the smaller zigzag inside one leg of that sequence, most often inside a pullback.

The distinction matters in practice because it explains a lot of apparent contradictions. In the figure, a trader watching internal structure sees a downtrend inside the pullback, then a bullish CHoCH as the pullback ends. A trader watching external structure sees an uninterrupted uptrend: a higher high, then a higher low. Both are right about their own level. A popular approach is to take the direction from external structure and the timing from internal structure, for example buying an internal bullish CHoCH near an external higher low.

Internal and external are relative terms, and the boundary between them is another rule you must define. Often it is the timeframe: the four-hour swings are external, the 15-minute swings inside one four-hour leg are internal. Sometimes it is the size of the swing rule: N = 5 for external, N = 2 for internal. Our guide to multi-timeframe analysis and the lesson on using several timeframes explain how to stack charts without drowning in labels.

Market structure and classic trend analysis

Market structure in forex is classic trend analysis with new names attached. The table translates the most common terms:

Market structure term	Classic equivalent
Higher high / higher low (HH/HL)	Uptrend in Dow theory
Break of structure (BOS)	Trend confirmation: a new high (or low) in the trend’s direction
Change of character (CHoCH)	First lower low in an uptrend (or higher high in a downtrend); a possible reversal
Internal structure	Minor trend, the swings inside a pullback
External structure	Primary or intermediate trend on the chart in use
Liquidity above equal highs	Stops clustered above an obvious resistance level

Seen this way, the method has the same strengths and weaknesses as any trend-reading tool. It is a clear, objective-looking description of what price has done. It lags, because a swing can only be confirmed after it forms. And it works well in clean trends and poorly in choppy ranges, where price breaks small swings in both directions and the labels flip back and forth. A moving average has the same problem from the other side, which is why the guide to moving averages in forex suggests reading it alongside swing structure, not instead of it.

What structure looks like in a range

Ranges are where structure labels cause the most trouble. Price rises to the top of the range and makes a “higher high” a few pips above the last one, which counts as a bullish BOS. Then it falls to the bottom, closing below the last higher low: a bearish CHoCH. A few days later the same thing happens in reverse. Every label is technically correct, and a trader who acts on each one buys near the top and sells near the bottom.

Two habits help. First, look at how far each break travels. A BOS that clears the old high by a handful of pips and stalls is weak evidence; one that runs well beyond it, by a meaningful share of the ATR, is stronger. Second, step up a timeframe. If the daily chart shows a flat sequence of roughly level highs and lows, treat the hourly BOS and CHoCH signals inside it as noise until price leaves the range. Our guide to range trading covers how to trade the range itself instead.

The Academy lessons on trends and break of structure and change of character go further, with practice charts for each label. If you want to use structure to time entries, the pullback trading guide shows the classic version: buy a higher low in an uptrend, with a stop beyond it.

The visualiser has the same trade loaded: entry 1.0751, stop 1.0724, target 1.0805.

Entry priceStop lossTake profit

Risk

Reward

Reward-to-risk

Win rate needed to break even

Break-even win rate = 1 ÷ (1 + R), where R is the reward-to-risk ratio. Costs push the real figure a little higher.

Trading on margin can lose you money quickly, and a structure label does not reduce that risk. Pip values here assume a standard lot of 100,000 units on EUR/USD in a US dollar account; check your own platform.

How reliable is a break of structure?

No public study we know of measures BOS or CHoCH signals under one agreed definition, partly because there is no agreed definition. Claims of high accuracy usually come from examples picked after the fact. What a trader can observe on any chart:

• Breaks fail regularly. Price closes beyond a swing and then reverses back through it. In a range, this can happen several times in a week.
• The signal arrives late. By the time a CHoCH is confirmed, a good part of the move against the trend has often happened, and the stop beyond the swing is a long way away.
• Results depend on the rules. Changing the swing rule, the close-or-wick rule or the timeframe changes the signals, as the two-rule figure above shows.

Try the replay. EUR/USD has been trending up and has just closed below its last higher low. Decide what that tells you before you reveal the rest.

EUR/USD has made higher highs and higher lows, and a candle has just closed at about 1.0724, below the last higher low near 1.0730. Many structure traders would call this a CHoCH. What do you do?

Sell now: the trend has reversedTreat it as a warning and stop buying; wait for more structureIgnore it: the higher timeframe is up

A change of character that fails. The close below the last higher low looks like the end of the uptrend, then price rallies to a new high within a few candles. Illustrative prices.

Costs also bite harder than they look. Structure stops sit beyond swing points, so on lower timeframes they can be only 10 to 15 pips away. A typical spread of around 1 pip on EUR/USD is then close to a tenth of the risk on every trade, before any slippage when the stop is hit. A rule that breaks even before costs loses money after them, and the lower the timeframe, the larger that drag. Count the spread in every test result.

Testing is the only way to know whether a structure rule adds anything for you. Write the rule in full, scroll a chart forward one candle at a time, record every signal it gives, and judge it on at least 50 trades in R, after spread. The Academy lesson on testing a structure idea honestly sets out the process, and the testing a strategy lesson covers sample sizes and curve fitting.

Common market structure mistakes

Labelling swings by eye

If you cannot write down why a peak counts as a swing high, you will count it when it suits the trade you want. Use a fixed rule such as the two-candle rule, and apply it even when the result looks odd.

Mixing timeframes in one sentence

“The trend is up but there is a CHoCH” is meaningless without timeframes. Say “four-hour uptrend, 15-minute bearish CHoCH inside the pullback”, and the picture becomes clear and testable.

Treating a CHoCH as a reversal

A change of character is the first sign that a sequence has broken. Many become pauses or ranges, and some are followed straight away by a new high, as the replay shows. Decide in advance what confirms a reversal for you.

Moving the swing to fit the stop

Placing a stop beyond the “real” swing only after the nearer one is hit turns structure into an excuse. The stop goes beyond the swing your rule identified when you entered. Our guide to where to place a stop loss covers structural stops in detail.

Believing the labels reveal bank activity

BOS and CHoCH are names for patterns in price. Nothing on a retail chart shows who traded, and the forex market has no single order book to read. Use the terms as a tidy description, and judge them by tested results, not by the story attached to them. If you like zones as well as swings, our guide to supply and demand zones applies the same standard.

Frequently asked questions

What is market structure in forex?

It is the pattern of swing highs and swing lows on a chart. Higher highs and higher lows describe an uptrend, lower highs and lower lows a downtrend, and roughly level highs and lows a range. Traders use the sequence to judge the trend and to place stops beyond the last swing.

What is the difference between BOS and CHoCH?

A break of structure (BOS) is a close beyond the last swing point in the direction of the trend, so the trend continues. A change of character (CHoCH) is the first close beyond the last swing point against the trend, such as a close below the last higher low in an uptrend. A CHoCH is a warning, not a confirmed reversal.

How do you identify a swing high or swing low?

Use a fixed rule. A common one says a swing high is a candle whose high is above the highs of the two candles on each side; a swing low is the mirror image. The rule can only confirm a swing after two more candles close, so it always lags slightly. Larger rules give fewer, bigger swings.

Should a break of structure be a close or a wick?

It depends on your rule, and you should choose one and keep it. A wick rule reacts sooner but counts many false breaks, where price pokes through a swing and falls back. A close rule waits for a candle to close beyond the swing, which filters some false breaks but gives a later, more distant entry.

Is market structure the same as smart money concepts?

Market structure is the classic higher-high and higher-low trend definition, which goes back to Dow theory. Smart money concepts add labels such as BOS, CHoCH, order blocks and liquidity, often with claims about bank behaviour. The labels describe price; the claims about who is trading cannot be checked from a retail chart.