I haven't been able to quickly find a good example of accumulation, but here is one of the examples from Masters of the Market:
Point (a)
We have a wide spread down on high volume, which is normally an indication of weakness (selling pressure).
However, over the next few days the market has not fallen – in fact it is up. If the high volume seen at point (a) had been selling, how can the market drift upwards?
To be more accurate, there was selling at point (a), but for the market to have gone up, the selling must have been 'absorbed' by professional traders.
They will only do this if they have become bullish. In this particular chart, we see the beginnings of an accumulation phase.
Point (b)
We observe an up-bar, but look at the volume: It is low. The market is unlikely to go up on low volume (no demand), which is why the market now moves sideways.
Low volume shows that either:
1. There is a shortage of stock at this price level due to the absorption volume seen at point (a),
OR
2. The professionals who are accumulating stock have withdrawn from the market, as they do not want higher prices – it is too early for them, as the floating supply has not been removed.
You have come to these logical conclusions because of point (a), which had to be absorption of the supply, by professional traders (an indication of strength).
Points (c) & (d)
Are small tests. Note the low volume at these points, which is an indication that the tests were successful and that supply has been removed.
The market cannot go down on low volume. Taken in isolation the actions at (c) & (d) mean little, but because you have seen absorption volume in the background, they now become strong buy signals.
Once you have seen very high volume on a down-day (or bar) on your chart, this shows high activity in the market.
If a rally starts due to the market-makers buying (or absorbing) the selling from weak holders who are being shaken-out on the lows, the market will frequently re-test this high volume absorption area, bringing the market back down into the reversal area (where the high volume was first seen) to make sure that all the selling has, in fact, disappeared.
You will know immediately if all the serious selling has disappeared because the volume will be low as it penetrates back into the old high volume price area. You would be wise to pay attention to this observation because it represents an excellent buy signal.
In summary, to mark a market down challenges the bears to come out into the open.
The low volume of activity shows that there is little selling left from the bearish side of the market.
There is now an imbalance between supply and demand caused by the recent shake-out (at point (a)). If there is little or no supply left in the market, this clearly shows that the trading syndicates and market-makers have been successful in their attempt to absorb selling from the weak holders, and that prices are now set to rise.