CarMax is a leading retailer of used cars and related services in the United States. The company operates a network of automotive superstores, offering a wide selection of high-quality used vehicles, as well as providing financing options, vehicle appraisals, and extended warranties. CarMax aims to provide a hassle-free car buying experience for customers, with a focus on transparency and customer satisfaction.

Currently, the stock of CarMax is selling off after retesting a significant base. The stock's price has encountered resistance at this level, leading to a decline in price as sellers step in. This suggests that the stock needs more time to consolidate and establish a stronger base before potentially resuming an upward trend. 

It is important to closely monitor the stock's price action and volume to assess whether the selling pressure subsides and the stock begins to stabilize. Patience is advised, as the stock may require additional time to base before presenting a more favorable investment opportunity.