Break of Structure (BOS)
In Smart Money Concept and market structure analysis, a Break of Structure occurs when price closes beyond a prior significant swing high (in an uptrend) or swing low (in a downtrend), confirming continuation of the existing trend structure.
Market structure in SMC analysis was built on the sequence of higher highs (HH) and higher lows (HL) in uptrends, and lower highs (LH) and lower lows (LL) in downtrends. A Break of Structure (BOS) was the event that continued or extended the existing sequence: in an uptrend, a BOS occurred when price closed above the most recent prior swing high, creating a new higher high. In a downtrend, a BOS occurred when price closed below the most recent prior swing low, creating a new lower low.
The distinction between BOS and Change of Character (CHoCH) was definitional: a BOS confirmed trend continuation, whereas a CHoCH (Change of Character) was the first sign of trend reversal — the first time the structure was broken in the opposite direction to the existing trend. Practitioners mapped the sequence of BOS events to track the trend and looked for CHoCH signals as potential reversal alerts.
In Nifty 50 daily charts, BOS events at multi-month swing highs were considered structurally significant. A BOS of the October 2021 all-time high would have been a structural bull confirmation at a major level; a BOS of a major swing low represented a structural bearish shift. The timeframe of the BOS determined its significance: a BOS on a weekly chart carried more structural weight than a BOS on a 15-minute chart.
The concept of a BOS was closely related to the classical technical analysis concept of confirming a breakout. The addition of the SMC framework was the integration of BOS with liquidity sweep, order block, and FVG concepts to build a fuller picture: a strong BOS was considered more meaningful if it occurred after a prior liquidity sweep that trapped participants on the wrong side of the trade.
Practical traders in Indian markets used BOS signals on daily and 4-hour Nifty and Bank Nifty charts to confirm trend direction before drilling down to intraday timeframes for entry precision. The multi-timeframe application of BOS was part of the top-down analysis approach common in SMC methodology.