Shares of GrubHub GRUB lost 5% today in morning trading after Morgan Stanley downgraded the company from Overweight to Equal Weight, lowering its price target to $43 from $47.Morgan Stanley cited competition from Amazon.com AMZN as the reason for the downgrade. Analyst John Glass conducted a survey that showed 26% of Amazon Prime members tried Amazon restaurants delivery in the past 6 months, limiting the potential customers for GrubHub. Additionally, Analyst Brian Nowak noted that restaurants could subsidize one-hour PrimeNow delivery.Amazon’s acquisition of Whole Foods Market WFM has also increased Amazon’s potential for reaching customers. This deal has created more competition among grocery stocks as well, hurting stores like Costco COST, which was downgraded by Goldman Sachs earlier this month.Other food delivery services are gaining ground as well, such as UberEats, owned by Uber, and YelpEat24, owned by Yelp YELP. Nowak sees competitor UberEats “gaining traction.” For example, McDonald’s MCD has been increasing the number of cities where its franchise locations offer delivery through UberEats, just adding Baltimore today.Last week, GrubHub hit new all-time highs after Wedbush Securities’ analyst Aaron Turner said that GrubHub was a potential buyout target for Amazon after their Whole Foods Market acquisition. As of Friday’s close, GrubHub shares are up almost 27% year-to-date.GrubHub remains a Zacks Rank #3 (Hold). The company faces some heavy competition in the near future, but it still has positive year-over-year earnings growth for the current year and maintains some strength.The Best & Worst of ZacksToday you are invited to download the full, up-to-the-minute list of 220 Zacks Rank #1 "Strong Buys" free of charge. From 1988 through 2015 this list has averaged a stellar gain of +25% per year. Plus, you may download 220 Zacks Rank #5 "Strong Sells." Even though this list holds many stocks that seem to be solid, it has historically performed 6X worse than the market. See these critical buys and sells free >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Amazon.com, Inc. (AMZN): Free Stock Analysis Report Yelp Inc. (YELP): Free Stock Analysis Report GrubHub Inc. (GRUB): Free Stock Analysis Report Costco Wholesale Corporation (COST): Free Stock Analysis Report McDonald's Corporation (MCD): Free Stock Analysis Report Whole Foods Market, Inc. (WFM): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research