The Hollywood Reporter reported on Monday that of those who tuned into the show in the U.S., just 37% completed the series.

Internationally, the show fared better, with 45% of viewers outside America watching the series in its entirety.

Industry insiders consider a 50% completion rate to be solid, but unspectacular, according to THR.

The publication cited unnamed sources familiar with the matter. Amazon did not respond to Fortune’s request for comment, but Amazon Studios head Jennifer Salke told THR: “This desire to paint the show as anything less than a success—it’s not reflective of any conversation I’m having internally.

“The first season required a lot of setting up.”

With an estimated $1 billion invested in the making of the series, the show is thought to be the most expensive television program ever produced.

Despite the reported completion rates, the series did have a strong start, with Amazon claiming the first two episodes were streamed more than 25 million times during their first 24 hours on its streaming platform—making it Amazon Prime’s biggest premiere ever.

A month into its release, Salke told Variety the show was approaching 100 million viewers.   

Amazon has committed to making five seasons of the show.

The company bought the adaptation and production rights to J.R.R. Tolkien’s novels about Middle-earth from the late author’s estate for $250 million in 2017.

However, its investment hasn’t, as yet, been enough to unseat Netflix’s domination in the original content space.

Data from Nielsen shows that last year, all 10 of the most popular original streaming series were made by Netflix.

Amazon’s The Boys came in 11th, while The Rings of Power came in 15th place, with 9.4 billion minutes watched.

Some of the higher ranked programs did have more episodes available than The Rings of Power, however.

New Harry Potter series in the works

News of the lackluster series completion rate for The Rings of Power comes amid reports that rival platform HBO is nearing a deal to start production on a Harry Potter television series, using its own fantasy fiction rights to entice fans to its streaming platform.

The series, adapted from the fantasy phenomenon, would see individual seasons dedicated to telling the stories of each of the seven Harry Potter books, Bloomberg reported on Tuesday.

According to Bloomberg, the CEO of Warner Bros.—HBO’s parent company—convinced author J.K. Rowling to produce the series, but the deal has not yet been completed.

The author has, in recent years, received backlash over her comments about the transgender community.

Warner Bros. previously turned the Harry Potter books—which have been translated into 80 languages and sold more than 500 million copies globally—into an eight-movie series, with the franchise also spawning a stage production, video games, merchandise, and studio tours.

Despite the success of the Harry Potter franchise, many fans have been skeptical about the reported remake of the original movies.

“This is going to completely bomb…There’s just no way your average Harry Potter–obsessed person will care about this without the original cast,” one Twitter user wrote on Tuesday.

“I see this failing miserably,” another said. “The movies are great and to be honest unbeatable.”

Others said they would rather Warner Bros. focused on telling other stories based on the books, such as the origin story of villain Lord Voldemort.

Toward the end of last year, Warner Bros. confirmed that there was no longer a fourth movie being developed in the Fantastic Beasts series, which is based on Rowling’s Wizarding World and serves as a prequel to the Potter stories.

The movies became embroiled in controversy when two of their stars, Johnny Depp and Ezra Miller, landed in legal trouble, with the studio ultimately replacing Depp.

The third film in the series, The Secrets of Dumbledore, reportedly had the lowest opening weekend in Harry Potter history.