Google (NASDAQ:GOOG) and Yelp are rumored to be in advanced acquisition negotiations according to a source with TechCrunch. The source reports that the deal could be worth over $500 million. Yelp is a local business review website that has become very popular since starting in 2004. Yelp receives about 9 million monthly unique visitors (comScore). However Yelp reports themselves that they receive 25 million monthly unique visitors.

Yelp’s annual revenues is roughly $30-$50 million. The company raised $31 million from venture capital firms, spread out in about four rounds of funding. Based on the venture capital investment, Yelp’s valuation is around $200 million. There is about an 80% chance that the deal will go through.