This heavy volume is due to derivatives, someone agreed to buy at these prices more than six months ago. We donot know if it is a correction in bull phase, or something more than that.
Heavy volume on the downside is bearish. It pays to sit back until the line is clear.
In today's volume even if you bought tons, it will be a drop in the market trend.
A low volume rally near the close is always a fooler of the major trend.
Stock trends always have reason to move in direction, a major change always creates problem for folks who simply buy without understanding the reason. I will add if there is block activity an up move near the close and stock picks more than 25 cents.
A few weeks ago Biotech got hit, now it is turn for some other group.