With this in mind, it is no surprise that Carvana's stock tanked when CarMax reported surprisingly bad second-quarter earnings. CarMax's earnings per share ( EPS ) dropped to $0.79 in the quarter, down 54% year over year. With used car prices still through the roof and interest rates rising, too, making it difficult for consumers to finance purchases, demand has fallen off a cliff. Even though CarMax gained market share in Q2, units sold decreased 6.4% year over year, and vehicles bought from consumers and dealers were down 8.1% from the prior year. Weakening demand indicates that used car prices could fall soon, which would further hurt CarMax's earnings and margins.