Stocks rallied in lighter volume Friday, with the major indexes retaking their 50-day moving averages. The S&P 500 drove 1.3% higher while the Nasdaq tailgated at 1.2%. The IBD 50 lagged with a 0.4% gain. Volume eased across the board. The 50-day moving average has been a battleground area since late March. The Nasdaq and S&P 500 popped above the line Friday after losing and regaining the line a handful of times in recent weeks.