MOUNTAIN VIEW, Calif. — The Federal Trade Commission is in the advanced stages of an investigation into YouTube’s handling of videos aimed at children, according to two people with knowledge of the inquiry.

The investigation, which could result in fines against YouTube, comes after complaints by parents and consumer groups that the video giant had collected data of young users.

The groups also complained that YouTube allowed harmful and adult content to appear in searches for children’s content, said the two people, who were not authorized to speak about the investigation because it was private. In addition, misinformation and inappropriate content appeared in YouTube’s recommendation engines, according to the complaints.

The F.T.C. is pursuing the investigation of YouTube as regulators and lawmakers in Washington are signaling their interest in curbing the power and influence of some of the biggest tech companies. The agency is poised to announce a settlement with Facebook over the social network’s handling of user data and potential violations of a 2011 consent decree with the agency over previous privacy violations.