I'm actually encouraged by the fact that we moved up 2.4% on low volume.
The way I see it, big moves up or down on high volume are par for the course; whenever the rate of trading increases, the SP is expected to fluctuate in response to the volume. Likewise, trading straight across on high or low volume is a yawn-fest; it means nothing, there are equal proportions of buyers and sellers.
However, movement up or down on low volume is indicative of a trend, imo. In order for the SP to move on low volume, there has to be a fairly wide gap between the bids and the asks, with few on either side willing to budge. If the SP moves down on low volume, that's bad - it means that sellers are willing to part with their shares at a loss (relative whatever the SP may have started at that day), but there are few buyers to absorb and eliminate those ask's, so the price falls easily. On the other hand, moving up on low volume, that's good - it means that sellers are demanding a higher price than is being bid and buyers are willing to pay extra to purchase their shares.
I'm sure there are holes in my little theory and board members are welcome to correct me and suggest their own ideas. I admit, I haven't thought about it much, but I have thought about it. Long story short, I don't think it's the volume that matters, but the direction the price is heading relative to high or low volume that matters.
With that said, Happy Fourth everyone! Geez, I'm gone all day and I come back to a board with 16 messages on it. Go to a BBQ or something, guys!
"I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it." -- Thomas Jefferson