Check out the companies making headlines before the bell: CarMax (KMX) – The auto retailer’s stock slumped 12.7% in the premarket after its quarterly profit and revenue fell well short of estimates. CarMax earned 24 cents per share, compared with a consensus estimate of 70 cents, and its comparable used-vehicle sales were down 22.4% versus FactSet’s consensus forecast of a 16.9% slide. Micron Technology (MU) – Micron shares fell 2.9% in the premarket trading after the chip maker reported a wider-than-expected quarterly loss and revenue that fell short of Wall Street forecasts. Micron’s results were impacted by declining demand for electronics, and the company announced it will cut about 10% of its workforce. Under Armor (UAA) – The athletic apparel maker named Marriott executive Stephanie Linnartz as its new CEO, effective on Feb. 27. Linnartz is currently president of Marriott’s international operations and has been with the hotel operator for 25 years. Tyson Foods (TSN) – Tyson is expected to lose hundreds of employees when it consolidates corporate offices in Arkansas next year, according to people familiar with the matter who spoke to the Wall Street Journal. The beef and poultry producer is closing two offices in Illinois and one in South Dakota. Tyson fell 1% in premarket action. MillerKnoll (MLKN) – MillerKnoll gained 2.9% in premarket trading after reporting better-than-expected profit and revenue for its latest quarter. The furniture maker was able to make up for a 13% decline in orders with higher prices. Earlier reports had said the company could cut as many as 700 employees as it refocuses on research and development of self-driving trucking technology. TuSimple rallied 3.5% in the premarket. Global Business Travel Group (GBTG) – The American Express spin-off was rated outperform in new coverage at Evercore ISI, which expects the business travel platform to benefit from its leading position in the industry and from a rebound in business travel recovery. Global Business Travel Group rose 1.6% in premarket trading. Mirati Therapeutics (MRTX) – The drug maker’s stock jumped 9.4% in the premarket after the FDA granted its colorectal cancer treatment a “breakthrough therapy” designation. That designation fast tracks the approval process for treatments that provide substantial improvement over existing therapies.