As far as rebound efforts go, Tuesday's bullishness wasn't exactly what the optimists wanted to see. The gain didn't undo all of Monday's damage, and the advance the market was able to muster was a low-volume effort. Generally speaking, for a move to have any follow-through, it needs more – not less – participants.

Take a look. Clearly, there's something going on with the 200-day average line (green). One day doesn't make a trend though. Indeed, one day didn't even stop the bigger-picture pullback presently underway.

Maybe it will. Maybe it's going to be a multi-day process. Or, maybe the lack of trading volume behind the effort speaks loudly and clearly about the lack of faith that a rebound is looming.

Makes sense. The sellers have been more persistent now than they've been in well over a year, and nobody can really argue that the gains seen since late 2016 have been unusually consistent. Now it's time to make up for lost time, injecting the profit-taking that should have unfurled several times in 2017.

And Tuesday's lack of volume is the big red flag… though the 20-day moving average line's move under the 100-day line isn't exactly something to dismiss.