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CoStar Group ™ Exhibit 99.1 CoStar Group First Quarter 2021 Revenue Increases 17 % Year - over - year with Traffic to CoStar Group Platforms up 47 % Year - over - year WASHINGTON April 27 , 2021 - CoStar Group , Inc. ( NASDAQ : CSGP ) , the leading provider of commercial real estate information , analytics , and online marketplaces , announced today that revenue for the quarter ended March 31 , 2021 , was $ 458 million , an increase of 17 % over revenue of $ 392 million for the first quarter of 2020 . Net income for the first quarter of 2021 was $ 74 million , or $ 1.88 per diluted share . Non - GAAP net income for the first quarter of 2021 ( which excludes amortization of acquired intangible assets , stock - based compensation , and other items as described below ) was $ 108 million or $ 2.75 per diluted share , an increase of $ 18 million or 20 % versus the first quarter of 2020 . EBITDA for the first quarter of 2021 was $ 136 million , an increase of 35 % versus EBITDA of $ 100 million for the first quarter of 2020. Adjusted EBITDA ( which excludes stock - based compensation , acquisition and integration related costs and other items as described below ) for the first quarter of 2021 was $ 160 million , an increase of 29 % compared to adjusted EBITDA of $ 124 million for the first quarter of 2020 . " Our business delivered a strong start to 2021 , with revenue and profit ahead of forecast and record numbers of visitors to our platforms in the first quarter of the year , " said Andrew C. Florance , Founder and Chief Executive Officer of CoStar Group . " Our sales team generated $ 52 million in company - wide net new bookings in the first quarter of 2021 , an increase of 10 % year - over- year . CoStar Suite net new bookings in the first quarter increased 77 % year - over - year , with both net new sales and renewal rates returning to the levels we achieved in 2019 , prior to the pandemic . We expect this positive momentum to continue during the remainder of 2021 , supported by the recent addition of both Commercial Mortgage - Backed Securities data and STR hospitality data in CoStar Suite , and the launch of the new CoStar international version earlier this month . " " Our marketplace businesses , along with Ten - X , also delivered very strong year - over - year results in the first quarter , " continued Florance . " Apartments.com revenue increased 21 % , network visitors were up 35 % , and quality leads to our customers grew 63 % . LoopNet and Ten - X continued to gain traction as our new marketing campaigns increased awareness and site traffic . Unique visitors to our LoopNet network increased 34 % and LoopNet Signature Ads revenue grew 50 % in the first quarter of 2021 compared to the first quarter of 2020. Ten - X's unique monthly visitors rose 45 % sequentially in what is typically a seasonally slow quarter , and the average number of bidders per auction grew 68 % year - over - year . " " We were excited to have the Homesnap team join us at the end of 2020 , " noted Florance . " The business performed well in the first quarter of 2021 , growing pro forma revenue by over 40 % year - over - year as paid subscribers more than doubled and subscription revenue grew by 68 % . "