The Dow Jones Industrial Average (DJIA) and the other stock indexes continued the sell-off that began last week. Today, the DJIA plunged more than 600 points in the first trading session after Standard & Poor’s lowered the U.S’s long-term credit rating to AA+. The S&P 500 had a worse day in percentage terms dropping more than 7% and breaking below its 200-week moving average (see chart).