Weak earnings from several large companies and a credit rating downgrade of several regions in Spain raised concerns about a slowing global economy... The Dow Jones industrial average finished the day down 1.8 percent, or 243.36 points, to end at 13,102.53, its worst performance since June. The losses added to the big declines on Friday, and dropped leading indexes to their lowest levels since early September, before the Federal Reserve announced its latest monetary stimulus program.