U.S. stock mutual funds advanced 0.41% in scoring a fifth straight week of gains, according to Lipper Inc. data. It’s their longest winning streak since a six-week romp that ended in early August last year. The latest gain put the average U.S. stock fund up 6.75% for the year. Funds that track the S&P 500 index, a proxy for the broad stock market, still lead the pack with a 12.54% year-to-date advance.