Shares of U.S. Auto Parts Network Inc. rose 8 percent on Thursday on news that a Laguna Beach investment company had accumulated a more than 5 percent stake in the aftermarket auto parts retailer

Maguire Asset Management LLC said in a Securities and Exchange Commission filing that between May 13 and July 10 it had accumulated 1.7 million shares of the Carson e-commerce company, making it the fifth-largest shareholder. The company is described as a private investment company whose principal is Timothy Maguire.

Maguire, who could not be reached for comment, did not say in the filing whether he intended to become actively involved in improving the fortunes of his new investment.

U.S. Auto Parts Network, whose online operations include USAutoParts.net, AutoMD.com and AutoPartsWarehouse.com, has been losing traffic to competing auto e-commerce sites and struggled to adjust to policy changes at online marketplace eBay, where it had a significant presence. The company also had problems integrating its 2011 acquisition of Chicago competitor Whitney Automotive, which it bought in a deal valued at $27.5 million.

Before today, shares had fallen 78 percent since the company announced a reorganization last August that consolidated sites to concentrate on those considered most viable.

Shares on Thursday closed up 8 cents, or 8 percent, to $1.04 on the Nasdaq.