After a dull first half of the year or so, Nio (NIO -4.99%) stock rebounded dramatically to gain almost 65% in the month of September alone. However, Nio's rally seemed unsustainable at least in the short run, and the electric vehicle (EV) stock ended October down 23.7%, according to data provided by S&P Global Market Intelligence.In particular, Nio's numbers failed to live up to investors' expectations, but there's no need to panic. Investors in Nio stock should, instead, watch out for the Chinese electric ...