Home improvement chain retailer Lowe’s Cos. Inc. is ending the year with an acquisition to boost business in its e-commerce channel.

Lowe’s, No. 91 in the Internet Retailer Top 500 Guide, is acquiring ATG Stores, an online retailing company that operates more than 500 home improvement and related microsites, for an undisclosed amount.

Lowe’s is acquiring ATG Stores, which says it carries an inventory of more than 3.5 million products in categories such as lighting, plumbing, furniture, hardware, appliances, decor, children’s products, sporting goods, outdoor living and apparel, to broaden its online retail base and attract more diversified shoppers. “The addition of ATG Stores is a strategic fit, providing more opportunities for Lowe’s to be a relevant partner at every stage of the home improvement process and deliver better customer experiences,” says Lowe’s CEO Robert Niblock.

Lowe’s will operate ATG Stores, which began operations in 1999, as a separate and independent unit, the retailer says. ATG Stores CEO Gary Rubens will oversee the new unit. “Lowe’s commitment to consumers, innovation and long-term strategy, combined with our unique online product offering, presents a long-term opportunity for ATG Stores and Lowe’s to grow in the multichannel space,” Rubens says.

ATG Stores, which operates LightingUniverse.com, FixtureUniverse.com, HomeFurnitureShowroom.com, FloorsandSurfaces.com and other sites, doesn’t break out web sales. But the company also says its operation is growing with sales that increased 80% in fiscal 2011. ATG Stores, which is based in Seattle, employs about 250 workers and also operates four stores in Washington state. The retailer launched a mobile commerce site in August.