Stocks rumbled higher in lower volume Friday, turning the major indexes positive for the week despite two days of heavy-volume selling. The Nasdaq advanced 1.6%, its best gain in more than two months. The S&P 500 and the Dow Jones industrial average rose 1% and 0.7%, respectively. The IBD 50 surged 1.8%. Volume shrank on the NYSE and the Nasdaq. Friday was an options expirations day, making the lower volume somewhat surprising.