Guessing the weekend box office is a game played by everyone from the people who actually made the movies to the auds lining up at the local multiplex. But the launch of two movie trading exchanges will soon enable folks to back up their forecasts with real cash.

The Commodity Futures Trading Commission is expected next week to give the greenlight to the Trend Exchange, created by Media Derivatives’ Robert Swagger, while the Cantor Exchange, owned by the Hollywood Stock Exchange’s Cantor Fitzgerald and run by Andy Wing, will bow at the end of April. Both will enable industry observers to buy into the performance of films over their first four weeks at the megaplex.

Even before their debuts, however, the exchanges have triggered contemplation of the possible benefits to the biz as well as worst-case scenarios that might hit Hollywood and change the way it operates.

On the upside, it’s possible the major studios and indies could mitigate losses on their riskier films by trading futures contracts. And that reduction of risk could also attract additional investors.

“By offering speculators and hedgers a market-based solution to transfer the considerable financial risks associated with major movie productions, the Trend Exchange will perform the same public service that futures exchanges have been providing to commercial users for nearly 200 years,” Swagger says.

Among the worst-case scenarios, however, one envisions actors’ quotes being dictated by how popular they are on the services. Another sees agents betting heavily on their clients’ films, or independent producers earning considerable coin from the prospects of their films getting picked up at film festivals and going on to become hits with moviegoers.

But the exchanges don’t work that way: Films available to trade must be wide releases and play on at least 650 screens, and traders can’t own more than 10,000 contracts per film.

Wing is adamant that the Cantor Exchange is strictly sticking to movies for the time being — properties whose proof of success can be clearly proved with box office results.

It may eventually offer TV shows, videogames and record albums down the line, the success of which can be supported by ratings and sales figures, but individual actors won’t be offered as trades, as their impact on a film’s performance is just too hard to quantify. Offerings may also expand to cover worldwide B.O. figures, especially on day-and-date releases.

Unless they actually invest, studios won’t benefit from the trades, considering they don’t officially make their movies available on the exchanges. Legally, wide releases are considered public domain and available for futures trading without approval from the studio, according to the CFTC.

However, trading will be closely monitored not only by the exchanges’ operators but also government orgs like the CFTC and the National Futures Assn., which tracks 300 different exchanges.

While the names of investors are not revealed, their identities and industry affiliations are known as part of the application process when getting approval to buy and sell contracts on the exchanges.

Individuals can be prosecuted for insider trading, just as they are on Wall Street.

“We face the same kind of scrutiny,” says Wing, CEO of Cantor Entertainment. “It’s prosecutable. Anyone who has non-public information and trades on it is putting themselves at risk.”

But in an age in which blogs cover every detail of a film’s development from script to screen, determining just how someone might possesses inside information on a film’s financial prospects could be hard to prove.

Wing does cite distribution heads at studios who know of release-schedule moves, screen-count changes or the amount of P&A being spent within two to four weeks of a movie’s bow as an example.

Reviews from early test screenings and word-of-mouth generated from messages sent on social networking sites like Facebook and MySpace or via Twitter already affect a movie’s B.O. haul.

And just as the Hollywood Stock Exchange and its virtual trading for films provided industryites and the media with fodder for how buzzworthy a film might be, a real exchange of dollars is sure to be scrutinized even more.

When figuring out which films to unspool, exhibitors could monitor trades to schedule more screens for a particular title or drop that count for another.

“Exhibitors now have a way of hedging box office performance,” Wing says. “It gives them a mechanism to help their economic forecasting.”

That could force marketing mavens to pony up additional coin to buy “contracts” of their films to give audiences the impression that their movies will be hits and are worth seeing.

The exchanges have long been in the works, but they had to convince government orgs that box office results provided an accurate enough figure to determine pricing before they could start doing business.

“Part of it was the government getting comfortable with a new asset class to be traded,” Wing says. “There has never been an entertainment futures exchange before.”

Both will essentially serve as brokerage houses, charging 25¢ per transaction as a commission. Trading starts six months before a film bows, but continues 24-hours-a-day up through the fourth weekend.

The Cantor Exchange, which hopes to bow April 22, once approved by the CFTC, will launch with 40 films, starting with April 23’s “The Losers.” Tentpoles like “Iron Man 2,” “Robin Hood,” “Shrek Forever After,” “Prince of Persia: The Sands of Time,” “The A-Team,” “Toy Story 3,” “The Twilight Saga: Eclipse,” “Sex and the City 2” and “Harry Potter and the Deathly Hallows: Part I” are also on the list, which ends with “The Chronicles of Narnia: The Voyage of the Dawn Treader” on Dec. 10.

Rounds of practice trading already were analyzed during demonstrations of the Cantor Exchange at ShoWest in Las Vegas.

Results showed that thousands of traders expect Universal’s “Repo Men” to earn $39.5 million during its initial monthlong run domestically, while Fox’s “Diary of a Wimpy Kid” is expected to bring in $45.5 million and Sony’s “Bounty Hunter” should haul in $64 million.

Whether that’s a bet worth making remains to be seen.