After only two weeks in theatres, Transformers: Dark of the Moon has sparked $261 million in North American box office receipts to roll into the number one film spot for 2011.

The sequel raked in $47 million in expected sales over the weekend and bypassed The Hangover Part II, to become the highest-grossing film of the year to date. Michael Bay’s big budget action film starring Shia LaBeouf focuses on alien robots in a quest to save the world.

Someone needs to save bosses Kevin Spacey and Jennifer Aniston in the weekend’s second-biggest hit, Horrible Bosses. In this dark comedy, abused employees played by Jason Bateman, Charlie Day and Jason Sudeikis conspire to kill their supervisors.

The weekend’s other big comedy, Zookeeper, opened at number three with an estimated $21 million in sales. Trailing behind was the animated sequel Cars 2, which made $15.2 million in its third week.

Bad Teacher, dropped from number three in last week’s rankings to number five with $9 million in box office receipts. And in sixth place, Julia Roberts and Tom Hanks teamed up for Larry Crowne, mustering $6.2 million in the film’s second week. Super 8 dropped two spots to number seven with $4.8` million, while tween flick Monte Carlo brought in $3.8 million at the number eight slot.

Superhero action flick Green Lantern dimmed to the ninth biggest film of the week with $3.1 in sales and Mr Popper’s Penguins managed to stay in the top 10 with $2.8 million.