The sixth instalment of Harry Potter has given Hollywood studio Warner Bros. its seventh No.1 hit of the year and has pushed the studio's domestic gross past the $1 billion mark.

The success of "Harry Potter and the Half-Blood Prince" comes on the heals of the studio's recent comedy "The Hangover", which, with more than $235 million in ticket sales thus far, has become the highest-grossing R-rated comedy ever domestically.

Warner Bros. has said in a statement released Sunday that it is the only studio to earn $1 billion annually for nine consecutive years.