The market is selling off fairly hard today and volume is coming in at a good clip.  If (AND I MEAN IF) this selloff gathers steam and heads south, there is an area of support on the Dow to watch to put new capital to work.  This is a methodology I use that computes support and resistance using the Fibonacci series which creates support and resistance bands.  When there is confluence with other support/resistance levels, the confidence level in the band is raised.  Notice in the lower band that there is a 50% retracement level of the July - August advance.  You also have the June 11 high of 8877.93 which needs to be checked.  That should provide solid support.

The range of the bands is: 8775 - 8934.  If the August 17 low of 9116.52 comes out, people will be declaring this market done.  That will create a classic bear trap.  For now, be patient and let things play out.