CoStar Group Inc. completed its acquisition of LoopNet Inc., an online commercial real estate marketplace with 5.8 million registered members and approximately 3.6 million unique monthly visitors. The transaction was initially announced in April 2011. It closed for $860 million.

“We believe our products and services, diversified client base, comprehensive geographic footprint and economies of scale will drive significant synergies, which we believe can lead to increased stockholder value and a stronger, integrated platform for our customers,” said CoStar Founder and CEO Andrew C. Florance in a statement.

CoStar will continue to operate LoopNet as a separate brand. The combined company, offering information, marketing and analytics for the commercial real estate industry, will retain the CoStar Group Inc. name and will trade on the NASDAQ Global Select Market under the symbol CSGP.