All three of the major indices reversed off of the area around the 50% retracement level. Look for the sell off to continue through the rest of the week with a possible up day coming this Friday with options expiration. A break below 740 on the SP500 I think would be solid evidence of a new down trend beginning. As the selling continues watch for positive divergence to develop on the 15 and 60 minute charts to serve warning of the approaching bottom.