Shares in AutoZone ( AZO) fell Wednesday as investors focused on flat same-store sales rather than a better-than-expected profit in the second quarter. In the quarter ended Feb. 14, the company earned $91.7 million, or $1.04 a share, vs. $79.3 million, or 79 cents a share, a year ago. The consensus forecast of analysts was $1.00 a share, according to Thomson One Analytics. Revenue at the nation's No. 1 auto parts chain rose 3.4% to $1.16 billion. Same-store sales, however, were flat. The company opened 45 new stores in the quarter. In premarket trading, shares in the Tennessee-based company were down $4.50, or 5.1%, to $83.90.