The electric vehicle stock is giving investors plenty of reasons to stay bullish.Rivian Automotive (RIVN 2.65%) stock gained a staggering 84% in the three months between May and July. That seemingly unstoppable rally ground to a halt last month, with the electric vehicle (EV) stock losing 13.9% of its value in August, according to data provided by S&P Global Market Intelligence. Rivian shares remain under pressure and are down another 4% this month, as of this writing.What's going on with Rivian stock?Rivia ...