"We intend this report to be the continuation of an ongoing discussion about commercial data practices, and user privacy," said Khan, who noted that the data collected could also crop up as an issue in merger reviews.
For the report, the FTC requested information from AT&T, Verizon Wireless, Charter, Comcast's Xfinity, Alphabet Inc.'s Google Fiber and T-Mobile as well as advertising firms associated with AT&T and Verizon.
The agency staff found that the companies collected data about browsing histories, what is streamed, sensitive characteristics like race and sexual orientation and real-time location, which they found were sometimes shared with third parties.
The report also found that some ISPs kept consumer data for a set period of time but others said they kept it as long as needed.
"The report found that even in instances where internet service providers purported to offer customers some choice with respect to how their data was collected or used, in practice users were often thwarted by design decisions that made it complicated, difficult or near impossible to actually escape persistent tracking," Khan said.
The FTC took oversight of ISPs in 2017 from the Federal Communications Commission. Khan, however, said she would "fully support efforts to reassert that authority."
Google and Verizon declined comment while the others did not immediately respond to a request for comment.
(Reporting by Diane Bartz; Editing by Mark Porter)