Washington, May 12 : Robert Downey Jr and Gwyneth Paltrow starrer 'Iron Man' has topped the weekend box office for the second week running with a collection of 50.5 million dollars.

The superhero film continues to make big bucks after raking in 100.8 million dollars at its opening.

In second place on the top weekend grossing list was the Emile Hirsch starrer 'Speed Racer' which raked in 20.2 million dollars, as per figures compiled by Exhibitor Relations.

Following closely in third place was Ashton Kutcher and Cameron Diaz's 'What Happens in Vegas' with an earning of 20 million dollars.

The top five was rounded off by the Patrick Dempsey, Michelle Monaghan starrer 'Made of Honor' that raked in 7.6 million dollars, and Greg Kinnear's 'Baby Mama' which earned 5.8 million dollars. The two movies came in fourth and fifth place respectively.

The list of top-grossing weekend films is as follows:

1. The Iron Man, 50.5m USD

2. Speed Racer, 20.2m USD

3. What Happens in Vegas, 20m USD

4. Made of Honor, 7.6m USD

5. Baby Mama, 5.8m USD

6. Forgetting Sarah Marshall, 3.8m USD

7. Harold and Kumar Escape from Guantanamo Bay, 3.2m USD

8. The Forbidden Kingdom, 1.9m USD

9. Nim's Island, 1.3m USD

10. Redbelt, 1.1m USD