 Tortoise Acquisition Corp. NASDAQ:SHLLs stock price gapped down prior to trading on Monday . The stock had previously closed at 47.78, but opened at 46.25. Tortoise Acquisition shares last traded at 46.00, with a volume of 1,364 shares changing hands. The companys 50-day simple moving average is 32.54 and its 200-day simple moving average is ... 