(CNN) -- "Wall Street: Money Never Sleeps" has an appropriate subject for a sequel: money.
The follow-up to the 1987 film "Wall Street," which premieres this week at the Cannes Film Festival, is following in a sturdy Hollywood tradition -- extending stories and characters in search of a bigger bottom line. It's a strategy that almost never fails, says S. Mark Young, a professor at the University of Southern California's Marshall School of Business.
"Sequels definitely have higher [box office] returns than nonsequels. In fact, it's about 30 percent more," says Young, basing his findings on an empirical study he and two colleagues, James Gong and Wim Van der Stede, conducted of 132 sequels produced between 2000 and 2006. Those returns come despite higher production costs for the follow-ups (though, Young says, they have slightly lower marketing costs).
Certainly, in recent years, Hollywood's profits have been built on the backs of science fiction, fantasy, action and comic-book films -- stories that often come presold, have wide appeal and offer easily extended brands. This summer is seeing the usual plethora, including the blockbuster "Iron Man 2," the Pixar sequel "Toy Story 3," and new chapters for "Sex and the City," "Twilight," George Romero's "Dead" series and "Cats & Dogs."
Though many films are now made with sequels in mind, that's not always the case, points out University of Nebraska film professor Wheeler Winston Dixon -- though box office returns can quickly change plans.
"Nobody thought 'Saw' would take off. Now it's a franchise," he says, reeling off other films -- such as "The Terminator," "Austin Powers: International Man of Mystery" and "First Blood" -- as films that initially were going to be one-offs.
The journey of the new "Wall Street" -- now slated for its American opening September 24 -- has been particularly unlikely, coming more than 20 years after the original.
The first film earned an Oscar for Michael Douglas' performance as corporate raider Gordon Gekko, famed for his "Greed ... is good" speech, but though successful, wasn't a huge blockbuster. Still, the indelible character allegedly inspired a generation of Wall Street traders, and in 2007 "Wall Street's" producer, Edward Pressman -- with Douglas on board to return -- cut a development deal with 20th Century Fox.
Eventually Stone signed on and a new script took shape involving Gekko -- just freed from prison, his 1980s-era brick cellphone in tow -- an ambitious young trader (Shia LaBeouf) and Gekko's daughter (Carey Mulligan), set against the financial meltdown of 2007-08.
Though the 23-year time lapse between films is unusual, it's not unheard of -- and Hollywood will turn to almost any promising project for a sequel (or its close cousin, the remake), says Dixon.
"Sequels and remakes go back to the dawn of film history," he says.
In fact, he points out, one of the earliest narrative films, Alice Guy Blache's "La Fee aux choux" ("The Cabbage Patch Fairy"), from 1896, was such a hit that it was followed by a remake and sequels. The so-called "Golden Age" of Hollywood didn't skimp on sequels, with such films as "King Kong" and "The Thin Man" quickly followed by new chapters, and the film "Dead End" spinning off almost 20 years of Dead End Kids/East Side Kids/Bowery Boys flicks.
Even "Casablanca" almost prompted a sequel, but the pre-video practice of regular re-releases made it financially unnecessary -- though it did spawn at least two TV series.
However, in the words of William Goldman's Hollywood dictum, "Nobody knows anything" -- and sequels are no guarantee of profits. That's particularly true for less sequel-friendly genres, such as hard dramas, romances and comedies, says Young.
Indeed, he points out, in today's Hollywood, stories are prized as much for their offshoots -- fast-food meals, action figures -- as their stories. Disney recently passed on a sequel to one of 2009's biggest hits, "The Proposal," because the film has no merchandising prospects, Young says.
"Everything is tied to profit," he points out. Deals are struck based on opening weekend box office; if that doesn't meet expectations, a declining revenue scale kicks in. "These days, the opening weekend is simply an advertisement for all the other downstream possibilities. If that fails, everything else fails."
And with movies more expensive than ever and a global market rife with piracy, every last dime has to be squeezed out of a story, adds Dixon. Some moviemakers use the knowledge of scheduled sequels to take risks, but in general the product is very much more, more, more of the same.
Overall, says Young, studios have relatively little to lose, particularly on the first sequel. After that, there are concerns that audiences may get tired of the franchise -- but there's always that remake or reboot for those who wait long enough.
Warner Bros. founder Jack Warner knew the score decades ago, says Dixon.
"Great movies aren't made," Warner reportedly said. "They're remade."