Best Buy Co. (BBY) stock is tanking, but CEO and Chairman Hubert Joly claims to be unfazed, as this is nothing new. "We're interested in the daily fluctuations of the share price, but our management team, as shareholders would like us to, is focused on long-term performance," Joly said on a company media call Tuesday, Sept. 19. Best Buy's investor day is set to start at 2 p.m. EDT on Tuesday, but midday, shares dived around 8% to $52.64 on disappointing revenue guidance.