> ## Documentation Index > Fetch the complete documentation index at: https://docs.chicago.global/llms.txt > Use this file to discover all available pages before exploring further. # Breadth > Understanding breadth - the share of stocks participating in a market move Breadth is the share of stocks participating in a market move, whether an advance is carried by most of the market or by a narrow handful of large names. ## Beginner ### What It Means An index can rise for two very different reasons: because most of its stocks are rising, or because a few giant stocks are rising enough to drag the average up while the typical stock goes nowhere. Breadth tells the two apart. ### Example Imagine an index at a new high while the median stock in it is below its own recent high. The advance is narrow: a handful of mega-caps are doing all the lifting. Now imagine the same index level reached with most stocks advancing together, same headline, far sturdier foundation. ### Why It Matters Breadth shows how widely a market move is shared. An index rising while the median stock falls has concentrated leadership. Broadening participation provides additional support for the trend; narrowing participation highlights its dependence on fewer constituents. *** ## Advanced ### How to Read It In the reports, breadth appears as a component of the [composite market-sentiment score](/glossary/composite-market-sentiment-score) and in the sector and market internals discussion. "Deteriorating breadth" during a rising market is a caution flag, the index is being carried by fewer shoulders. Improving breadth during a recovery is a sign the move has foundations. ### Common Misreadings * **Treating narrow leadership as an immediate sell signal**: narrow markets can stay narrow for long stretches, breadth is a fragility measure, not a timer * **Reading breadth without the index**: falling breadth in a falling market is ordinary; falling breadth in a rising market is the pattern worth attention, the divergence carries the information * **Equating breadth with sector rotation**: rotation moves leadership between groups; breadth measures how many stocks participate at all, a market can rotate healthily or narrow unhealthily, and the sector analysis section distinguishes the two ### Reading It Against the Other Measures Breadth is the participation check on [momentum](/glossary/momentum): a strong trend confirmed by broad participation deserves more trust than the same trend carried by a few names. When the reports pair a positive sentiment reading with a breadth-led warning, that pairing is deliberate. ### Related Terms Where breadth is a component The trend breadth confirms or questions The classification breadth feeds