Inc.’s (AMZN) Prime subscription service may have peaked in the U.S., which could prompt the company to expand its offerings on that front.

That’s according to RBC Capital Markets, which said in a research report that while the Seattle-based e-commerce giant has seen double-digit growth in Prime during the past few years, that wasn’t the case in May. In a research report covered by, RBC analyst Mark Mahaney said that penetration rates for Prime in the U.S. increased from 25% in June 2013 to 55% in May 2018. Still, as of May, the growth was unchanged when compared to June of last year. noted it's the first time since the analyst started the survey four years ago that there wasn’t growth in Prime's U.S. numbers. (See also: America Has Become the United States of Amazon.)

Amazon Boosts Price of Prime

"This is a bit of a surprising result, especially given that Amazon recently reported 100 million Prime subscribers globally," said Mahaney in the report, according to "This implies Amazon's Prime membership expansion is likely driven by growth in international markets." In addition to disclosing it has 100 million Prime members, Amazon announced a few weeks back that as of May 11, the cost of Prime membership was increasing to $119 from $99 a year. Back in 2014, it raised it to $99 from $79 per year.  

According to the RBC analyst, while Prime’s value proposition is still “compelling,” it will have to enhance it with more videos, music and speedier shipping to see its penetration increase. He noted that even with the price hike, Prime is a good value. (See also: Microsoft Working on Tech to Challenge Amazon Go: Report.)

Amazon Expands Across the Pond

RBC's  call out comes at a time when Amazon is trying to expand its content offering, which could drive more demand for Prime. Earlier this month, it announced a new deal to broadcast soccer games from the English Premier League. The e-commerce giant will live broadcast 20 soccer matches a year for three years in the U.K starting in August 2019. It marks the first time that a tech company has won rights to show Premier League games in the country, ending Sky PLC and BT Sports’s five-year hold on sports broadcasting rights. Amazon said in a statement that members of its Prime Video service are "guaranteed" to see the team that they support play live on the platform.