Market Breadth

Market breadth measures how many stocks are participating in a market move—whether most stocks are going up or down together, or if only a few are driving the action. You'll hear analysts mention it when they're trying to figure out if a market rally is genuine or fragile. It matters because a healthy market move usually has broad participation; if only a handful of mega-cap stocks are surging while thousands of others lag behind, that's a warning sign. For example, if the overall market index rises 2% but only 30% of stocks in it actually gained value, that's weak breadth—suggesting the rally might not last. Think of it as checking whether the whole team is winning or just the star players.