The Federal Communications Commission has leveraged nearly $200 million in fines against wireless carriers AT&T, Sprint, T-Mobile and Verizon for illegally sharing customers’ location data without their consent.

“These carriers failed to protect the information entrusted to them. Here, we are talking about some of the most sensitive data in their possession: customers’ real-time location information, revealing where they go and who they are,” FCC Chairwoman Jessica Rosenworcel said in a statement released Monday.

Officials first began investigating the carriers back in 2019 after they were found selling customers’ location data to third-party data aggregators. Fines were proposed in 2020, but carriers were given time to argue against the claims before the fines were imposed.

The FCC argues that the four firms are required to take reasonable measures to protect certain consumer data per federal law.