Spider-Man 2, the film sequel starring Tobey Maguire and Kirsten Dunst, looks set to break the five-day North American box office record.
The film opened in the US last Wednesday
The movie, released in the US last Wednesday, is predicted to have made up to $155m (£85.6m), estimates suggested.
Distributor Sony has not yet confirmed details of the film's takings over the holiday weekend, but it took at least $64m (£35.5m) in its opening two days.
The total would beat Shrek 2's record five day haul of $129m (71.6m).
Other studios were predicting the film would make $90m (£49.7m) over the three-day weekend, despite the fact the 4 July holiday had fallen on Sunday this year.
"People are very distracted on the Fourth. Usually it's barbecues and fireworks, not movies," said Paul Dergarabedian of US box-office analysts Exhibitor Relations.
Record first day
The Friday-Sunday total of $90m was down on the three-day total of $114.8m ($63.4m) the first Spider-Man film took on release two years ago - though it had opened on a Friday, not a Wednesday.
Spider-Man 2 was also expected to break the North American record for the biggest haul in the first six days. On its first day it had made $40.5m (£22.5m), a record in North America for a single day.
Last weekend's top film, the Michael Moore documentary Fahrenheit 9/11, was at second place, taking an estimated $17m (£9.39m) over the three-day weekend.
It is now being shown on 1,725 theatres, and has taken more than $55m (£30.5m) in the US since its release.
Distributor Tom Ortenberg, president of Lions Gate Films, said the movie was on track to become the first theatrically-released documentary to make more than $100m (£55.5m).
"I can't predict, but I think we have a terrific chance. Regardless, the picture is an overwhelming success," he said.