GrubHub (GRUB) has seen its competitive positioning improved in two ways this week, said Guggenheim analyst Matthew DiFrisco, who points to reports that Amazon (AMZN) is shuttering Amazon Restaurants in the U.S. and the company's announcement that it raised $500M of unsecured debt.While Amazon Restaurants didn't establish meaningful market share in any major market, the exit removes a potential investor of incremental capital into the food delivery category and further substantiates the hyperlocal barriers to entry, according to DiFrisco. After he the debt offering, the analyst estimates the company will have about $150M of additional cash that it can use for opportunistic investments that could be accretive to growth, he added. DiFrisco reiterated GrubHub as his Best Idea with a $120 price target and Buy rating.