Updated from 9:10 a.m. ESTCarMax ( KMX) shares skidded Tuesday after record fourth-quarter earnings and first-quarter guidance from the used-car retailer both fell short of analysts' expectations. Net income increased 18% to $22.5 million, or 21 cents a share, compared with $19.1 million, or 18 cents a share, in the year-ago period. The fourth quarter results included a gain of 1 cent a share on the sale of a new car franchise. Analysts were expecting 21 cents a share, according to Thomson One Analytics. Revenue rose to $1.12 billion in the quarter ended Feb. 29, from $946.6 million a year ago, at the specialty retailer of used cars. The Richmond, Va.-based company also forecast EPS of 33 cents to 35 cents in the first quarter and $1.21 to $1.26 for the full year. Analysts are calling for 36 cents and $1.26 a share. Shares fell 24 cents, or 0.8%, to $28.47.