Fifty Shades Darker is doing significantly worse at the box office so far than its predecessor, Fifty Shades of Grey.

Fifty Shades Darker has grossed $50.5 million in the four days it has been out in theaters, and while this already makes it one of the top grossing movies of 2017, it's not so impressive in comparison to the first film in the franchise.

Fifty Shades of Grey, which came out in 2015, grossed $93 million in its first four days and reached $100 million within its first six days. As for Fifty Shades Darker, it looks like it's going to take a lot longer to reach $100 million at this rate.

The opening weekend for Fifty Shades of Grey was an impressive $85 million, while the Fifty Shades Darker opening weekend dropped by about 50 percent, grossing $46 million. To make matters worse, Darker actually opened in more theaters than Grey (3,710 vs. 3,646).

It's also hard to imagine that Fifty Shades Darker will come anywhere close to Fifty Shades of Grey's total box office: $166.1 million. Unless the sequel has major legs in the coming weeks, it's not looking good.

One major factor for the drop in box office sales may have been the reviews. Critics have torn apart the Fifty Shades sequel, with an abysmal 9 percent (out of 100) on Rotten Tomatoes.

"Actively dull and astoundingly flaccid, the monotonously dreary, everlastingly humdrum BDSM fan fiction franchise can never quite decide if it'd rather be smutty or classy," says The Playlist.

"The film's sex scenes ... start to get a bit grating after a while," says The Boston Globe. "There are too many of them, and even when accessories are added, I found myself groaning (not in a sexy way), desperate for more narrative."

Fifty Shades Darker is out in theaters now.