US stocks posted a modestly volatile trading session Friday, as investors took a breather after major stock indices rewrote record book repeatedly in the past couple of weeks. In midday trading, the blue-chip Dow Jones Industrial Average advanced 5.02 points, or 0.03 percent, to 16,484.90. The S&P 500 edged down 0.34 point, or 0.02 percent, to 1,841.68. The Nasdaq Composite Index shed 6.91 points, or 0.17 percent, to 4,160.27. The market toggled in and out of negative territory after initially moved up at the open, as investors were reluctant somewhat to take new positions after the U.S. stocks had staged a run of gains in the past ten days. On the previous trading session, the Dow and the S&P 500 extended their record run, buoyed by better than expected jobs data. Despite a light volume in the Christmas holiday-shortened week, major stock indices are exhibiting a lukewarm "Santa Claus" rally with momentum gradually building up in the absence of major headwinds toward the end of the year. With no major economic calendar, the U.S. stock market is expected to continue to move back and forth in the afternoon trading session. The three major stock indices are on track to finish the week on a positive note for a second week in a row. In overseas markets, stocks in Europe saw an across-the-broad rally Friday after the two-day Christmas break, propelling the German DAX index to a record high. Asian stock markets also rallied broadly Friday, with the Japanese Nikkei notching a fresh six-year high.