 Shares of CarMax Inc. KMX, 2.79 took an 11.9 dive in premarket trading Thursday, after the used vehicle seller reported fiscal third-quarter profit and sales that dropped well below expectations, as inflation and rising interest rates led to vehicle affordability challenges. Net income for the quarter to Nov. 30 fell to 37.6 million, or 24 cents a share, from 269.4 million, or 1.63 a share, in the year-ago period, to miss the FactSet consensus for earnings per share of 65 cents. 