Stocks kept a grip on gains Friday as the indexes made up for the previous session’s givebacks. The Nasdaq opened 1.2% higher and then rose to finish up 1.5% for the day. The S&P 500 and the Dow Jones industrial average each added 1.2%. The IBD 50 sprinted 1.8%, leading the indexes for a second straight session. Volume in the stock market fell on both major exchanges.