SMC Market Structure Explained: BOS, CHoCH, MSS and Internal vs External Structure
Lesson 2 of 10 · Beginner
Swings: the bricks of market structure
Every structural analysis starts with a simple question: which high and which low count? In SMC these points are called the swing high and swing low. The most common definition is a three-candle pattern: a swing high is a candle whose high is above the highs of the candles immediately before and after it, and a swing low is the reverse. To reduce noise, some traders require two or three candles on each side instead of one.
Once swings are marked, trend is defined by their sequence: in an uptrend we see higher highs (HH) and higher lows (HL), and in a downtrend lower highs (LH) and lower lows (LL). This is the classic Dow definition; SMC adds nothing to it except a stronger focus on the break point and the liquidity around swings.
The key point is that structure depends on the timeframe. Gold may be bullish on the 4-hour chart while running a complete bearish correction on the 5-minute chart. Neither is wrong; you simply have to know which timeframe you are talking about.
BOS: a break of structure in the direction of the trend
BOS stands for Break of Structure and refers to the latest swing being broken in the direction of the current trend. In an uptrend, price trading through the latest high (HH) is a bullish BOS and shows the trend is continuing. In a downtrend, a break of the latest low is a bearish BOS.
The perennial debate is whether the break must be confirmed by a candle body close or whether a wick through the level is enough. The more cautious approach is a body close, because a wick that pokes through and returns quickly may actually be a liquidity sweep rather than a break of structure. Whichever you choose, keep it constant across all your analysis.
Hypothetical gold example (M15): suppose XAUUSD has made a higher low at 3,980 and a high at 4,020. If a candle closes above 4,020, say at 4,024, that is a bullish BOS. The low that led to the break, 3,980 or the last higher low before the break, now becomes the "protected low"; as long as it holds, the bullish structure on this timeframe remains valid.
CHoCH: the first sign of a change in character
CHoCH stands for Change of Character and refers to the first break of structure against the prevailing trend. In an uptrend, a break of the last higher low, the one that produced the latest high, is a bearish CHoCH. It does not mean "the trend has reversed"; it means "the behaviour of the market has changed and the uptrend is no longer healthy".
ICT material also uses a closely related term, MSS (Market Structure Shift), which usually requires the break to come with a strong, fast move (displacement). The practical difference is that many traders treat a CHoCH without a strong move only as a warning, while a break with displacement is viewed as a more serious sign.
Continuing the hypothetical example: after the 4,024 high, gold makes a low at 4,006, rises again to 4,031 and then closes below 4,006 with a large candle. That break is a bearish CHoCH on M15. If the 3,980 low is broken afterwards, the structure on this timeframe has become fully bearish. Until then, the market is in a state of "possible change".
External and internal structure
External structure (also called swing structure) refers to the major swings that form the overall range of movement, such as the 3,980 low and the 4,031 high in the example above. Internal structure consists of the smaller swings that form inside that range. A pullback within an external uptrend is, viewed internally, a small downtrend of its own.
Why does the distinction matter? Because many false signals come from mixing the two layers. An internal CHoCH on the 5-minute chart may only be the end of a pullback that continues the external trend. SMC traders commonly say: take direction from external structure, and take entry timing from internal structure.
Two more useful terms: a strong high or low is a swing that caused a break of structure and is expected to hold; a weak high or low is a swing that has not yet produced a break and is probably the next liquidity target. In an uptrend, the low is strong and the high is weak.
| Term | Meaning | Use |
| BOS | A swing broken in the direction of the trend | Confirms trend continuation |
| CHoCH | The first break against the trend | Warning of a change in behaviour |
| MSS | Structure shift with a strong move | A more serious sign of reversal |
| Strong / Weak | Protected swing or target | Defining invalidation and targets |
When structure misleads
Structure works well in trending markets and causes trouble in ranging ones. When gold oscillates in a neutral range between two levels, you will see a BOS and a CHoCH on the lower timeframes every few hours, and none of them follow through. The warning sign is breaks that keep returning with wicks while no move extends beyond the range.
Another danger is the release of major US data such as NFP and CPI. A news candle can break both the high and the low within seconds. Evaluate structure that forms at these moments with extra caution, and usually after the market has calmed down.
Finally, labelling structure after the fact is easy. Real practice means going back on the chart, moving forward candle by candle and deciding in real time which break is a BOS, then recording the outcome. That is the only way to measure your actual skill at reading structure.
Common mistakes
- Switching the break definition (body or wick) from trade to trade depending on which favours the analysis
- Interpreting every lower-timeframe CHoCH as a reversal of the main trend
- Mixing internal and external structure and taking direction from the 5-minute chart
- Analysing structure at the moment of a volatile news release without considering the nature of the news candle
- Insisting on reading a trend in a market that is clearly in a range
What does volume say here?
A structural break on the chart only says that price has crossed a level; volume and delta tell you whether the market accepted that crossing. A BOS accompanied by rising volume, sustained positive delta and continued trading above the broken level is usually a sign of acceptance. By contrast, a break made on low volume, or one where the footprint shows aggressive buyers above the high meeting heavy passive selling while price fails to advance (absorption), has a higher chance of reversing.
For a CHoCH, delta divergence helps: if gold makes a higher high but cumulative delta prints a lower high, buying pressure is weakening and the next CHoCH is more meaningful. In the Volume Profile, a shift of the value area in the direction of the break is independent confirmation of the structure change. These tools do not replace structure; they measure its quality. Remember that XAUUSD CFD volume is tick volume, and real volume comes from COMEX GC futures, translated to CFD prices with the live basis.
📊 See real gold futures volume behind these ideas: free order flow course · today's gold volume map
Frequently asked questions
What is the difference between BOS and CHoCH in Smart Money Concepts?
A BOS is a break of structure in the direction of the current trend and confirms continuation. A CHoCH is the first break against the trend and warns that market behaviour has changed, but on its own it is not a certain reversal.
Does a BOS need a candle body close, or is a wick enough?
Both definitions are common. A body close is more cautious and reduces false signals caused by stop hunts. What matters is choosing one definition and applying it consistently.
Which timeframes should I use for internal and external structure?
A common approach is to take direction from external structure on a higher timeframe such as H4 or H1 and time entries from internal structure on M15 or M5. The exact combination should be set by your own testing.
Education only, not a recommendation to buy or sell; we never give signals. Price examples are illustrative. Test any method on a demo account first, with strict risk management.