(Reuters) - Advance Auto Parts Inc (AAP.N) posted weak results and warned of challenging sales trends in the second quarter as the auto parts retailer struggles to attract more customers, sending its shares down as much as 18 percent.
The company reaffirmed its full-year profit outlook of $5.55 to $5.75 per share, while analysts were expecting a raise. Analysts were expecting $5.97 per share, according to Thomson Reuters I/B/E/S.
"Due to our slow start... we anticipate our business results will be constrained during our second quarter," Chief Financial Officer Mike Norona said in a statement.
Oppenheimer analyst Brian Nagel said the company could be losing market share to AutoZone Inc (AZO.N) and O'Reilly Automotive (ORLY.O) and expects weak results to continue.
Advance Auto Parts -- which sells parts, accessories, batteries and maintenance items to both do-it-yourself and commercial customers -- expects annual comparable store sales to be in the low single digits for 2012.
It had earlier forecast comparable store sales to be in the low to mid-single digit range.
Advance Auto said it would repurchase $500 million of its stock. The new plan replaces a $300 million share buyback program authorized in August 2011.
Net income for the first quarter rose to $133.5 million, or $1.79 per share, from $109.6 million, or $1.35 per share, a year ago. Sales increased 3.1 percent to $2 billion.
Advance Auto shares fell to a five-month low of $67.22 in early morning trading on Thursday. They were down 15 percent at $69.68 in afternoon trading on the New York Stock Exchange.
(Reporting by Kartick Jagtap and A. Ananthalakshmi in Bangalore; Editing by Viraj Nair)