U.S. stock markets headed lower Friday, potentially headed for the seventh day of losses out of the past eight trading sessions. Stock markets rose marginally Nov. 9. They have otherwise slumped since the Nov. 6 election, the Dow Jones Industrial average off 4.5 percent or 594 points since the close on Nov. 5. The Standard & Poor\'s 500 is off 4.65 percent or 66 points since voters went to the polls. Similarly, the Nasdaq index has lost 5.6 percent or 168 points. In late-morning trading Friday, the DJIA was off 21.04 points or 0.17 percent to 12,521.34. The tech-heavy Nasdaq composite index shed 6.53 points or 0.23 percent to 2,830.40. The S&P 500 dropped 3.65 points or 0.27 percent to 1,349.68. The benchmark 10-year treasury rose 4/32 to yield 1.581 percent. Before polls opened Nov. 6, 10-year notes were yielding 1.689 percent. The euro fell to $1.2704 from Thursday\'s $1.2782. Against the yen, the dollar rose to 81.26 from 81.17 yen. In Tokyo, the Nikkei 225 index gained 2.2 percent, 194.44 points, to 9,024.16.