Break of Structure (BOS) in Trading: Meaning, a Real SPY Chart and 33 Years of Data

Michael Whitman · Trading since 2017, full-time since 2020 · YouTube creator, 137K subscribers · Published 2026-09-06 · Updated 2026-11-02 · Reviewed 2026-11-01

Video: Michael Whitman on YouTube, a beginner's guide to break of structure. Watch it on YouTube.

Covered on this page: TradingView and LuxAlgo.

A break of structure (BOS) is a candle closing beyond the last swing point in the direction the trend is already going: above the last swing high in an uptrend, below the last swing low in a downtrend. The rest of this page shows how to mark one without hindsight, walks through two real SPY stretches, and tests on 33 years of SPY whether a break told you anything about what came next.

How it works

In an uptrend, price makes higher highs and higher lows. A break of structure is the moment a new high closes above the previous swing high — the sequence continuing, confirmed.

In a downtrend it is the mirror: a close below the previous swing low.

That is the entire definition, once the swing is defined. No indicator and no calculation beyond one setting: how many bars on each side a high must beat to count as a swing. The rule used on this page is five, so a swing high is a day whose high is above the highs of the five sessions before it and the five after it. Since five more sessions have to print first, nobody can mark that swing until about a week later.

The level exists before the event does, which is worth more than it sounds. Mark the last swing high while price is still below it and the decision point is fixed in advance rather than rationalized afterward.

Every structure break needs a swing point, and every swing point is confirmed late; a ten-bar QQQ swing high was confirmed with the close a median 3.69% below its peak (swing highs and lows).

The distinction that actually matters

Break of structure breaks WITH the trend. Change of character breaks AGAINST it. They are opposite events with nearly identical names, and confusing them inverts the read completely.

In an uptrend: a close above the last high is a break of structure. A close below the last low is a change of character. Same chart, same day, opposite meanings. The two are set side by side, with the market structure shift, in BOS vs CHoCH.

Use closes. A wick through the level is not a break by any usable definition — wicks poke through levels constantly on every timeframe, and treating them as structural events produces a signal every few candles. On SPY’s daily chart since 1993, price traded above 290 live swing highs; 121 of them were first crossed by a wick that closed back below. Ten sessions on, SPY closed above the level after 70 of those 121 wicks (57.85%) and after 115 of the 169 crossings made by a close (68.05%). The close leaned the right way, but not clear of chance (Fisher exact test, p = 0.08).

Even a close is not the last word: across five markets, 721 of 1,080 closes beyond a swing level were followed by a close back on the other side within ten bars, by the count in liquidity sweep vs break of structure.

A worked example

SPY’s daily chart from May to October 2025 is a clean chain. The read turned up on 12 May 2025, when SPY closed at $582.99 above the 25 March swing high of $576.41 — a change of character, because the read had been down, last confirmed by a downward break of structure on 3 April.

Then five breaks of structure in a row, each a close above the latest known swing high:

The chain ended on 10 October 2025. SPY closed at $653.02, below the 25 September swing low of $654.41, which had been known since 2 October. That close was a change of character down, and the string of breaks of structure stopped there.

Read the margins column before the last one. Two of the five breaks cleared the level by less than a dollar on a $600 share price. A swing rule of four or six bars would have drawn different levels and dated some of these breaks differently, which is why the rule has to be fixed before the chart is read.

And the 20-session column looks good only in hindsight. All five were higher 20 sessions later, but so were most stretches of 2025. The question is whether that happens more after a break than on any other day, which is what the data section below tests.

Does a break of structure lead to continuation?

Not reliably, on SPY’s daily chart. Using the same five-bar rule over the same 1993 to 2026 sample, each break was followed by some next structural event: either another break the same way or a change of character against it. After the 142 upward breaks of structure, the next event was another upward break 74 times (52.11%). After the 110 upward changes of character, it was an upward break 68 times (61.82%). A fresh break did not make the next one more likely than a fresh turn did; the gap runs the other way and is within chance (Fisher exact test, p = 0.13).

Downside breaks chained even less. After 56 downward breaks of structure, the next event was another downward break only 14 times (25.00%). Of the 109 completed down readings that began with a change of character, 68 ended at a change of character with no break of structure in between, and none ran past three. The longest upward chain was eight breaks in a row, starting in January 1995.

2026 shows what a choppy year looks like. From July to October 2026 SPY traded between $729.10 and $781.62, and the rule fired seven times. None of the three breaks of structure was followed by a second one:

That is the range failure in real prices. Each break was a correct description on the day it happened, and each was undone within weeks. The margins were small, too: the 10 September break cleared its level by $1.65 on a $758 share price.

In practice: a trend is a chain of these

Strung together, breaks of structure ARE the trend. An uptrend is literally a sequence of closes above successive prior highs.

Internal and swing structure are the same rule at two sizes. Smart money traders call a break of a small, recent swing an internal break and a break of a larger one a swing break. In the data below, that is simply the bar count: two-bar swings for internal, five or ten for swing.

The original data

The sample. 8,472 daily SPY bars, 29 January 1993 through 25 September 2026. The rule is the one in the worked example and on the market structure page: five-bar swings, each known five sessions after it forms; a newer swing replaces the older one the day it becomes known; a close beyond the live swing breaks it, and each level breaks once. A break in the direction of the current read is a break of structure, and the first break of the sample only sets the read.

That rule found 199 breaks of structure: 142 upward and 57 downward. The question here is what SPY did next. “Higher” means the close N sessions later was above the close on the break day, price only. The base rate is every session with N sessions still to come.

The day count is for the 20-session column; the five-session column has 8,467 days and 57 downward breaks.

Neither difference is distinguishable from chance. Tested exactly against the 63.91% base rate, the upward breaks give p = 0.49 and the downward breaks p = 0.68. Five sessions out, the upward breaks were actually higher a little less often than any day (p = 0.40).

A downward break did not mean lower. After 34 of the 56 downward breaks, SPY was higher 20 sessions later, and the median change was +1.84%. A long-rising market pulls every starting day upward, and the break did not overcome that.

Changing the swing width did not change the answer. With two-bar swings, 65.51% of 316 upward breaks and 65.91% of 132 downward breaks were higher 20 sessions later. With ten-bar swings it was 67.69% of 65 and 72.41% of 29. Each is within chance of its base rate.

One result out of 24 cleared the usual 5% bar, and it was not a break of structure: with five-bar swings, 70.00% of 110 upward changes of character were higher five sessions later (p = 0.012). Running 24 tests at the 5% level, about one such result is what luck alone produces.

Breaks also overlap. In 40 of the 141 gaps between upward breaks, the next one came within 20 sessions, so those windows share days and the effective sample is smaller than 142. Every event and its 5- and 20-session changes are in the SPY break of structure file.

The honest summary is that this is a description, not a signal. It tells you a trend is still doing what a trend does. That is worth knowing and, on SPY’s daily chart, it is not an edge, because what followed a break looked like what followed an ordinary day.

What it is not

It is not a signal to buy. It confirms a trend that was already visible. Buying the break means buying after the move that produced it, and the table above shows no extra follow-through to pay for that.

And it is not the same as a breakout. A breakout leaves a range. A break of structure continues a trend.

When it fails

A range breaks it completely. Price alternates between boundaries, so each swing closes beyond the last one in the opposite direction, and the tool produces breaks both ways on every leg. It is describing oscillation, not confirming a trend.

The second failure is entering at the break. By definition the move has already happened. On SPY’s daily chart the 20 sessions after an upward break were no better than any 20 sessions, so the break itself offered no extra reward for buying late.

A third is redrawing the swing after the fact. Which high counts as “the” swing high is a judgment, and moving it once price has moved converts a pre-marked level into a post-hoc explanation.

The use that survives all of that is as a state, not a trigger. While breaks keep occurring in one direction, the trend is intact by definition. When one stops occurring and a change of character appears instead, the state has changed.

Questions people ask

Does a break of structure need a candle close?

On this page, yes: a close beyond the level, not a wick. Conventions differ. On SPY’s daily chart, a swing high first taken out by a close sat above it ten sessions later 68.05% of the time; one first poked by a wick alone, 57.85%.

What is the difference between BOS and CHoCH?

A break of structure closes beyond a swing in the trend’s direction; a change of character closes beyond one against it and flips the read. BOS vs CHoCH compares them in full.

Do all breaks of structure lead to continuation?

No. On SPY since 1993, 74 of 142 upward breaks were followed by another upward break before a change of character, about half.

How is a break of structure different from a liquidity sweep?

A sweep pokes through a swing and closes back inside; a break closes beyond it. How often one turns into the other is measured in liquidity sweep vs break of structure, and the marking steps are in how to spot a break of structure.

Related

Change of character is the opposite event and the one this is most often confused with. Market structure is the framework both sit inside, and it counts how often each one fires. Smart money concepts is where both terms come from. Volume and the order book are the usual second checks at a break.

The last opposing candle before that break is an order block, and without the break there is no block to mark.

This page is educational, not financial advice. Test every idea on your own charts before risking money. Some links on this page earn a commission if you buy through them. It costs you nothing and it does not decide what appears here or in what order — how these pages are made is set out in our methodology.