The ranking, for the curious, comes when Forbes crunches numbers on a star's salary and compares it to the box-office take for his or her movies, including overseas figures. The formula's a little more complex than that, but you get the idea. So if you were a movie studio who hired Will Ferrell, you averaged $3.35 back for every dollar you paid to him. The Forbes article notes that comedians have the toughest time increasing the bang for the bucks paid to them because funny in the U.S. isn't necessarily funny elsewhere, and their foreign box office figures lag.
Earlier this year, Forbes also published a list of the best investments movie companies had made, and that list was topped by...Shia LaBeouf? Because the list takes into account box office over the past several years, and because LaBeouf wasn't paid all that much for the first installment of the blockbuster money-earner Transformers, a movie company that hired him made $81 for every dollar it paid him. Because actresses are usually either the centerpieces of smaller-grossing films or they're secondary characters in the larger-grossing action or super-hero blockbusters, they make up half of the top 10 best investment list. Although Anne Hathaway hasn't starred in anything with Transformers-level take, she made her bosses $64 for every dollar they paid her, based heavily on the $1 billion worldwide receipts for 2010's Alice in Wonderland and the two tween-fave Princess Diaries releases. That makes her tops for actresses and actually second to LaBeouf overall.
But there's no way to know if actors' box-office muscle will continue to grow along with their salaries. Yes, they were paid chump change for their last movie and it turned out to be a mega-blitz powerhouse at the box office, so negotiations start with a demand for the director's firstborn son to be raised as their own. This movie, though, may tank completely and not make enough to pay for the free popcorn the movie critics ate watching it. No guarantees on the investment.
Although I do feel safe in saying that no matter now much money either of them is paid and no matter how much money their movies make, any film that stars Will Ferrell, Shia LaBeouf or any combination thereof is pretty much guaranteed to suck.