The biggest fear when GrubHub (GRUB) plunged to $17 earlier this year was that competition from Amazon (AMZN) Prime, Uber, Yelp (YELP) and private firms would destroy the business model. In reality, GrubHub has taken a market leading position and customer loyalty program to push the stock back to previous highs. Original customers in Chicago and Manhattan from 7 years ago continue to spend more and more showing no signs of competition hurting demand. The only problem is that the market figured this out and sent the stock soaring back to $43 now. Trading at nearly 40x 2017 EPS estimates, I'm with Cowen that the stock might have a value of up to $38, but one definitely doesn't want to buy GrubHub at these levels expecting more upside. Disclosure: Long YELP