Analysts grossly underestimated the allure of 'Fifty Shades of Grey' at the box office

Analysts vastly underestimated how well "Fifty Shades of Grey" would perform at the box office President's Day Weekend.

The adaptation of the best-selling erotica fan-fiction series by E.L. James brought in an adjusted $85 million over the three-day weekend (originally that number was $81.7 million). In four days, the $40 million Universal Pictures and Focus Features' film made $94.4 million.

Analysts thought it would make just over $60 million.

That was probably due in part to comparisons with "Twilight." "Fifty Shades" started out as fan-fiction of the popular teen novels. The first "Twilight" movie debuted to $69 million in 2008, so an opening around $60 million would have made sense for the first installment of "Fifty Shades."

Instead, the film became the best-opening weekend in February ever at the box office, knocking 2004's "Passion of the Christ" from the top spot.

Here are a few other records it now holds:

• Largest opening weekend for a romantic movie (beating out 2001's "Pearl Harbor," $59 million)
• Largest opening weekend for an erotic thriller (topping 2009's "Obsessed," $28.6 million)
• The biggest R-rated ticket-seller on Fandango

The film also has the fourth-largest opening weekend for an R-rated movie.

Since its release, the movie has made over $266 million worldwide. In the UK and Ireland, the film made $21.5 million.

Why didn't analysts think "Fifty Shades" would make more?

For one thing, history precedes it.

Typically, February isn't a month where we see a lot of break-out box-office hits.

"The LEGO Movie" started to change that thought process last year when it surprised everyone with a $69 million opening weekend, and a second weekend where it nearly performed just as well.

The biggest thing "Fifty Shades" had going against it was how previous R-rated films and films in the erotica genre have performed at the box office opening weekend.

Take a look at the biggest opening weekends for R-rated movies. "Fifty Shades" is the only film of its kind to crack the top five.

Instead, here's how the top erotic thriller films have performed opening weekend at theaters:

"Fifty Shades" had the advantage of not only being an R-rated erotica film, but unlike the other films listed above, it had a huge "Twilight"-sized fan following. Over 100 million copies of "Fifty Shades of Grey" have been sold.

The combination of both helped it break any box-office expectations.