Chinese electric vehicle maker Nioheld its annual Nio Day event last weekend where it unveiled its latest new electric sedan. Though customers appear to be eager to purchase one, Nio stock's continued decline has resulted in a 22% drop in the stock's value over the past month. Today, shares dropped 1.03% and continued to slide 1.34% in extended hours.Nio hasn't put out any company-specific news today, but it introduced its new ET5 electric sedan last weekend, which it hopes will compete with Te