CarMax earnings, Starbucks union, Wayfair upgrade, Nikola truck fire: Trending stocks

CarMax shares are up as the company reports better-than-expected earnings amid its cost-cutting efforts. Starbucks stock slips as the union warns of strikes. Wayfair shares trade lower despite receiving an upgrade from MoffettNathanson. Nikola stock falls as semi-trucks caught on fire at the company's headquarters in Phoenix, Arizona. Yahoo Finance Live breaks down some of the trending tickers since opening.