From IMDB:
The Lord of the Rings: The Return of the King sold about $34.1 million worth of tickets at the domestic box office on Wednesday, setting a record for a Wednesday premiere and also setting the stage for what many analysts predict will be the biggest opening weekend for any film ever. The previous record for a Wednesday opening was set by Star Wars: Episode I -- The Phantom Menace in 1999, when it took in $28.5 million. New Line Cinema distribution chief Rolf Mittweg reported that the film earned an additional $23.5 million in 19 other countries, including $5.2 million from the U.K., where it also set a Wednesday record.
From Box Office Mojo:
Among all opening days, Return of the King's $34.1 million ranks third behind Spider-Man's $39.4 million and The Matrix Reloaded's $37.5 million, but ahead of the first Harry Potter's $32.3 million.
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Ultimately, Two Towers became the first sequel to an uber-blockbuster ($250 million plus) to out-gross its predecessor, $339.8 million to $313.4 million. Return of the King could become the second.