Zillow ( Z) ($90.05) is up 73.2% since June 6, and as a result of a parabolic move to $94 on Monday, the stock has been downgraded to sell from buy. The company provides real estate information for all who participate in the housing market, including buyers and sellers. Zillow was a failed IPO, and reports quarterly results after the close Tuesday with the expectation that the company will report a loss of 39 cents a share. My monthly value level is $79.65. Yelp ( YELP) ($54.01) is up a staggering 96.7% since June 6. The company provides an online community covering restaurants, shopping, nightlife, financial services and health care. Yelp beat second-quarter EPS estimates by 2 cents by reporting a loss of 1 cent a share on July 31. The stock popped in a parabolic bubble move from $41.80 on July 31 to $59.35 on Aug. 2, which caused a downgrade to sell from hold. My weekly value level is $52.00. Facebook ( FB) ($39.19) is up 66.6% since June 6 and on July 24 reported EPS of 13 cents a share beating estimates by 4 cents. The stock returned to its IPO price at $38 and beyond to a test of $39.32 on Monday. As a result of this parabolic move, the stock has been downgraded to sell from buy. At $23.52 on June 6 it was a buy. At $39.19 on Monday it's a sell. The company is arguably the poster child for what a social networking company should be. My weekly value level is $34.44. At the time of publication, Suttmeier had no positions in stocks mentioned.Follow @SuttmeierThis article is commentary by an independent contributor, separate from TheStreet's regular news coverage.