Portman tops Forbes' top-10 list of Hollywood's Best Actors for the Buck by returning USD 42.70 for every dollar a studio spends on her.
Portman leads the pack with her Oscar-winning turn in 'Black Swan', whose worldwide gross was USD 329 million though it was made on a small budget of USD 13 million.
The magazine added her other studio releases like 'No Strings Attached' and 'Your Highness' to reach the conclusion.
Stewart may have had a bad year due to her affair scandal with director Rupert Sanders but that did not hurt her financial viability.
She was second on the list with 'Twilight' franchise and 'Snow White and the Huntsman'. The young star returned an average of USD 40.60 for every dollar she earned. She is followed by Shia LaBeouf (USD 35.80) and co-star Robert Pattinson (USD 31.70).
Harry Potter star Daniel Radcliffe rounded out the top five list by returning USD 30.50 for every dollar that he earned. Another 'Twilight' star Taylor Lautner ranked 6th with a USD 29.50 return.
Bradley Cooper was ranked 7th for making USD 25 for every USD1 paid to him while Dwayne Johnson came 8th by returning USD 22.70 for every dollar. Actress Amy Adams was ninth by earning 22.60 for every dollar.
Kevin James, at 10th spot, was a surprise by making an average return of USD 22.40 per dollar.
The actors' contribution was calculated using information on their earnings from Forbes' Celebrity 100 list, box-office grosses and budget estimates, using "the last three films each actor starred in over the last three years that opened in more than 2,000 theaters," according to the announcement.
In the magazine's list of Most Overpaid Actors for 2012, actor Eddie Murphy came on top. He returned an average of just USD 2.30 at the box office for every dollar he was paid.
