 Shares of Tortoise Acquisition NYSE: SHLL were trading lower on Friday amid a sectorwide sell-off of stocks of electric-vehicle companies following an analysts post-earnings downgrade of Tesla NASDAQ: TSLA. As of 2:15 p.m. EDT, Tortoises shares were down about 9.8 from Thursdays closing price. Auto investors will recall that Tortoise is the special-purpose acquisition company that announced an agreement last month to merge with Hyliion, a maker of electric and hybrid powertrains for heavy trucks. 