Take a look at the chart of PHS. What is the significance such a high volume reversal bar. The volume today is 4.7mil and that is the highest volume it ever had for the year.
Here's another chart of a different stock, DST. It had a high volume reversal in August 6, on unusually high volume. I think it had a news event on that date. The stock eventuall retested its highs in Sep. Any one else have any insight on volume interpretation?
Volume is not to be used alone. At any rate this one is in solid congestion. Price channel is hi-lo of congestion.
The significance is pretty much illustrated in the second chart you posted - dst. Sellers lost a battle and it was a huge one - buyers will be in control for a while.
Many high volume reversals in recent years have proven to not be indicative of anything beyond the day. Volume studies, in general, are highly overrated.