If we then look at when we have the fewest downticks, we find that the next 10 days in SPY have averaged a gain of +.13%. When we have the greatest number of downticks, the next 10 days in SPY have averaged a gain of +.96%. Heavy selling tends to beget future buying. That's a value effect.

If we now combine total upticks and total downticks to create our participation measure, we find that when we've had the lowest participation, the next 10 days in SPY have averaged a loss of -.10%. When we've had the highest participation, the next 10 days in SPY have averaged a gain of +1.33%.

So this is what's essential: There are value participants in the marketplace that scoop up stocks when they have traded weakly. There are momentum participants in the marketplace that buy shares when they're moving sharply higher or lower. Market lows are created when value and momentum participants are interacting with one another, first selling falling shares, then scooping up the fallen assets, and then picking up the rising stocks. Market highs are created when prices get to the point where they no longer attract value participants and lose their momentum. There is relatively low participation at those times.