Web users face an even greater threat to their privacy as large ISPs align themselves more closely with data brokers to track their customers, an advocacy group said.

Several large ISPs have either formed partnerships with, or acquired, data tracking and analytics firms in recent years, giving them a "vast storehouse of consumer data," according to a report Wednesday from the Center for Digital Democracy.

"ISPs have been on a shopping spree to help build their data-targeting system across devices and platforms," the report says. "Superfast computers analyze our information ... to decide in milliseconds whether to target us for marketing and more."

Through digital dossiers that merge all of this information, we can be bought and sold in an instant -- to financial marketers, fast-food companies, and health advertisers -- all without our knowledge."

ISPs are increasingly using programmatic advertising "fueled by powerful alliances among data, media, advertising and technology companies," the report says. The new advertising model "encompasses nearly all the device and formats we rely on -- including mobile, audio and video."

Some ISPs now have the ability to marry a customer's Web surfing history with his or her TV viewing habits and mobile app use to target advertising across devices, the report says.

CDD has sent the report to the U.S. Federal Communications Commission, which is scheduled to vote next week on the first step toward tougher privacy rules for ISPs. Several ISPs have opposed the proposals, saying it's not necessary for the FCC to get involved in policing privacy.

Jon Banks, senior vice president at the trade group USTelecom, whose members include ISPs, said service providers are committed to protecting customer privacy. ISPs have been subject to privacy oversight from the Federal Trade Commission, as other Internet companies are, he said in an email.

"It’s curious that CDD seems to be asking the Federal Communications Commission to impose stricter obligations only on ISPs but is not pushing for the same consumer protections when it comes to other companies that have long used similar and more detailed data to generate enormous advertising businesses," Banks said. "Consumers deserve consistent privacy protections as they use the Internet."

The FCC's move toward new privacy rules for ISPs is related in part to the agency's reclassification of broadband as a regulated, common-carrier service in net neutrality rules passed in February 2015. Reclassification of broadband moved the authority for policing broadband privacy from the Federal Trade Commission to the FCC, privacy groups have said.

Other trade groups and large ISPs declined to respond, or didn't respond, to requests for comments on the CDD report.