On Wednesday, the market opened weak, and it ranged for most of the day. But at around 2:30  p.m., the market began to drop. The sell off lack volume for a big decline, but the move did wipe out 1/2 of the gains from Monday's strong up day. The Nasdaq fell -29 points (-0.72%), the S&P dropped -8 points (-0.47%), and the Dow lost -101 points (-0.61%). 

Volume on the Nasdaq and S&P were was lower for the second day in a row. Two days of lower volume raises the chances of a big range day tomorrow or the next day. Decliners led advancers by an 8-to-5 ratio and down volume out paced up volume by 9-to-4. 

Since the correction, the Nasdaq has been weaker than the S&P, and the Naz has already fallen to its 200 SMA. The S&P, however, has been holding steady above its 50 EMA. I think the S&P is the index to watch; if it drops below its 50 EMA, then this correction will likely be longer and deeper.