The Dow Jones industrial average and the S&P 500 held their ground in record territory in afternoon trading Friday, while the Nasdaq poked above the 4800 level, just a smidgen from a nearly 15-year intraday high set Nov. 28. The Nasdaq rose 0.7%; the S&P 500 gained 0.4% and the Dow climbed 0.3%. Volume was running lighter in the stock market today compared with the same time Wednesday. Selected airlines had a strong day.