Shares of Zillow Group Inc. (NASDAQ: Z)(NASDAQ: ZG) were down 16% as of 2:15 p.m. EDT Tuesday after the online real estate platform leader announced strong quarterly results relative to expectations, but followed with light guidance. Zillow also announced a large acquisition.On the former, Zillow's second-quarter revenue grew 22% year over year to $325.2 million, well within its latest guidance for a range of $322 million to $327 million.