Natalie Portman best actress for the buck

Academy award winner Natalie Portman, 31, topped Forbes list of best actors for the buck, providing about $42.70 for every dollar she earns.

Black Swan, for which she won her best actress Oscar, was produced for an estimated $13million and earned impressive $329million in global box office sales.

Twilight star Stewart, 22, was not far behind, bringing in $40.60. She also topped the Forbes list of highest-earning actresses with an estimated $34.5million in salary in 2012.

'Stewart was able to earn a ton over the last three years and offer a healthy return thanks to Twilight,' according to Forbes.com. 'Even though she was paid $25million to star in the last two films, she was clearly worth the money.'

For comparison, veteran comedian Eddie Murphy returns only $2.30 for every dollars he gets paid, making him the least bankable star in Hollywood these days.

The site analyzed salaries, estimated box office grosses from the actor's last three films that opened in more than 2,000 theaters over the previous three years to calculate the studio's return on investment. The most bankable stars tended to be featured in the most profitable films.

Besides Black Swan, Portman, who has been on hiatus to be with her young son, also starred in the high-grossing romantic comedy No Strings Attached opposite Ashton Kutcher.