Auto parts retailer Advance Auto Parts (NYSE: AAP) shares declined nearly 18% in the week through Thursday afternoon. For example, O'Reilly Automotive reported a 7.6% increase in its comparable-store sales in its quarter ending Sept. 30, and AutoZone's domestic same-store sales increased 6.2% in its quarter ended Aug. 27. To be fair, part of the reason Advance Auto Parts' sales lagged behind its peers comes down to a conscious decision to increase sales of owned-brand products.