Glossary term
Break of Structure
A move beyond a prior confirmed swing high or swing low.
Break of structure, often abbreviated BOS, is used by price-action traders to identify when market structure appears to shift in the direction of a trend. A bullish BOS usually means price closed above a prior swing high; a bearish BOS means price closed below a prior swing low.
Example: If SPY closes above the latest confirmed swing high, a rule-based system can label that as a bullish break of structure.