The Dow has been garnering all of the headlines of late, but the NASDAQ finally broke down below support two days ago and is setting a pretty ugly tone for the market.
NASDAQ June 4 1997 - 1404
NASDAQ Nov 19 2008 - 1420
The S&P 500 has not closed below 848 and has bounce 3 times off the 830 level, but we are at 827 right now. If the markets stay under this kind of pressure for the remainder of the day it could set up for an interesting end of the week (Friday is option expiration which generally adds to volatility).