How to buy stocks high and sell them low By: MarketWatch July 01, 2011 at 19:02 PM EDT ProShares Ultra Nasdaq Biotechnology ETF is up almost 30% so far this year. It’s also the Stupid Investment of the Week. Read More >> Related Stocks: Nasdaq Biotechnology Ishares ETF Standard & Poors 500 Ultra Nasdaq Biotechnology 2X ETF