Movie trailers have become their own kind of blockbusters.

Hollywood studios collectively spent $3.16 billion last year on U.S. marketing efforts to draw people to the theaters in the face of competition from new entertainment options, according to Nielsen.

The struggle to reach the mass audience has given rise to a diverse industry of producers that cuts feature films into bite-sized appetizers. About 15 years ago, there were only a dozen or so companies distilling motion pictures down to 2-minute previews. Now there are more than 100.

Fueling this growth has been an explosion in viewing online, where previews can generate as much buzz as the films themselves. People have watched more than 35 million hours of movie trailers on YouTube so far in 2015, up 90 percent from the same period last year.

“For us, it’s a heyday of trailer-making,” said David Stern, whose 10-year-old company, Create Advertising Group, has worked on campaigns for “Fantastic Four,” “Minions” and “Avengers: Age of Ultron.”

The rise of trailer companies is largely due to technology. New digital advances for filmmakers have made it easier and cheaper for aspiring trailer cutters to get started on their own, and the reach of YouTube means a bigger audience than ever.

Established players such as Trailer Park, Mark Woollen & Associates and Create Advertising have had their eyes on the broader market for years. But some start-ups have gained a foothold by appealing to specific demographic groups.

Soda Creative, based in the hip Arts District of downtown Los Angeles, is one of the companies that have sprouted up to take advantage of studios’ appetite for targeted marketing. Owner Jaime Gamboa has made a specialty of the burgeoning Latino market that has become increasingly important to Hollywood and driven the success of huge films such as “Furious 7.”

He and business partner Jaehoon Oh, who started Soda in 2013, try to amplify parts of the movie that will appeal to Latinos without pigeonholing them. Their “Guardians of the Galaxy” commercial for Univision, for example, highlighted the Disney superhero movie’s action and swagger, not its offbeat humor and 1970s pop music.

Disney also recruited Soda for its feel-good movie “McFarland USA,” about a white PE coach who leads a team of Latino cross-country runners. Disney desired a more “culturally rich” feel for the drama’s second trailer, Gamboa said.

It wanted a different song to play over the footage, replacing the U2 track used in the first trailer. Gamboa’s team and Disney ultimately landed on a song from Colombian rocker Juanes.

“The way other major agencies were approaching the Hispanic market was, to be frank, very archaic,” said Gamboa, 41, who is Mexican American. “We’re not coming at it from the perspective of ‘I’m Hispanic, so I know all about Hispanics.’ We’ve been involved in the research.”

The focus on Latinos appears to be working.

Gamboa’s staff has more than doubled to 12 full-time employees in the last year, and he says his revenue is growing at an annual rate of 40 percent to 44 percent. The company this month moved to a 4,000-square-foot space from a cramped temporary office.

The audience for trailers is not just diverse, it’s hungry, experts say. The explosion of online video has helped make trailer release dates into events that get their own promotional push. Studios increasingly hype teaser trailers that come out ahead of the full versions, and announce when they’ll unveil each new video to keep the audience interested for months leading up to opening weekend.

Websites such as YouTube have become the go-to place to view movie ads, especially for young people who aren’t trekking to the multiplex as often as their parents did. The second official teaser for “Star Wars: The Force Awakens” racked up 88 million online views on its first day alone, Disney said in April.

“The marketing of the marketing has become a prime secret weapon,” said Craig Murray, whose Los Angeles firm MOcean has helped with campaigns for Marvel’s “Ant-Man” and Warner Bros.’ “American Sniper.”