Amazon CEO Jeff Bezos. Emmanuel Dunnand | AFP | Getty Images

Amazon and a little-known energy company are Wall Street analysts' favorite stocks based on highest percentage of buy ratings. Both the online retailing juggernaut and Diamondback Energy are universally loved on Wall Street, with all analysts that cover the stocks rating them a buy. They are the only two out of 500 stocks where that's the case, according to FactSet.

CNBC used FactSet to screen all companies looking for the stocks with the highest percentage of buy ratings compared with total ratings. We threw out companies that had less than 10 analysts covering them. Amazon, the world's second most valuable company behind Microsoft, grew its share of the U.S. e-commerce market to 42% in 2018, according to J.P. Morgan. The bank expects Amazon, whose stock has surged more than 2,000% in the past decade, to surpass Walmart as the largest U.S. retailer in 2020. Amazon shares are up 23% this year. "The highest quality management and franchise within global internet – a must own name with huge upside even from here," Pivotal Research's Michael Levine said in a note to clients about Amazon. "AWS duration will surprise to the upside both on topline and EBIT and the move towards one day shipping is a significant step to owning the consumer's wallet."

Diamondback Energy?

Amazon's accumulation of 47 buy ratings on the Street may not come as a surprise given its dominance in the e-commerce space. However, tied for first place is oil and gas drilling company Diamondback Energy. Diamondback, which drills exclusively in the Permian Basin, reported last month that its oil and natural gas production more than doubled more than doubled from a year ago to 263,000 barrels of oil equivalent per day. The company was one the biggest energy sector gainers in May after the biding battle for Anadarko Petroleum. Analysts believe Diamondback shares will jump 64% over the next 12 months, based on their average price target collected by FactSet. In May, Bank of America Merrill Lynch added Diamondback to its prestigious US 1 list, with a $170 price target. The bank said shares of Diamondback have underperformed but its fundamentals have improved. "FANG remains a top pick on continued benefits from a transformational recent acquisition, top-notch execution, increased shareholder friendly initiatives and above-average oil leverage," Bank of America's Asit Sen said in a note to clients. Diamondback acquired rival Energen in a $9.2 billion deal last year. The shares are down 17% over the last month.

Health care loved