Stock investors, enjoy your gains but start protecting your portfolios By: MarketWatch December 04, 2017 at 10:05 AM EST U.S. stocks are sky high in this bull market, but they could fade fast, says Nigam Arora. Read More >> Related Stocks: Alphabet-A Alphabet-C Amazon.com Apple Facebook Intel Corp NVIDIA Corp PowerShares QQQ SPDR S&P 500 ETF Trust