LOS ANGELES — In what they hope will be an aggressive attack on the web-based theft of intellectual property, some of Hollywood’s top foreign sales executives are banding together to fight digital movie pirates.

Five small film companies — Millennium, Voltage Pictures, Bloom, Sierra/Affinity and FilmNation Entertainment — said they were forming a new antipiracy coalition with the aim of mobilizing small businesses in the television, music, game and software industries against online theft.

The alliance is calling itself the Internet Security Task Force. Millennium’s president, Mark Gill, described it as a last-ditch effort by relatively fragile companies with fewer than 50 employees to avoid what they say is the near destruction of their prospective blockbusters, as happened to Millennium and its partners with “The Expendables 3” last year.

“Maybe larger businesses can afford to take a hit,” Mr. Gill said in a phone interview last week. “But we don’t have that luxury, we can’t survive.”