After a scary morning sell-off, stocks rebounded and were trading mixed in the final hour of trading on little news and with volume lightened by the Columbus Day holiday. The Nasdaq was flat, the S&P 500 was down 0.2% and the Dow Jones was down 0.1% in the stock market today. But growth stocks were still staggered by the morning decline. Among IBD 50 stocks, 18 were up and 32 were down.