Definition
Accumulation is the market phase in which buyers absorb available supply, usually while the price trades sideways in a relatively narrow range. The classic interpretation is that better-informed or longer-horizon participants are building positions before a wider audience recognizes the opportunity.
On a chart, accumulation often appears as a flat, range-bound base after a decline. Selling pressure has exhausted itself, and demand begins to match or exceed supply without yet pushing the price decisively higher.
Why it matters
How it works
During accumulation, sellers who want out have largely been satisfied, so each new wave of selling meets steady buying interest. Volume frequently dries up across the base and then expands as the price approaches and breaks the top of the range. That volume expansion on the breakout is the signal most traders wait for.
Because accumulation is only confirmed in hindsight, practitioners treat a flat base as a candidate rather than a certainty. A failed breakout can reveal that the range was simply a pause before further decline.