US regulators moved to impose fines Friday against the nation's four major wireless carriers for selling location data of customers without their consent.

The Federal Communications Commission proposed fining T-Mobile more than $91 million; AT&T some $57 million; Verizon $48 million, and Sprint $12 million.

The wireless firms were accused of having disclosed mobile network user location data to a third party without authorization from customers, the FCC said.

The FCC began an investigation after a report that a sheriff in Missouri used a "location-finding service" operated by a prison communications services company called Securus to track whereabouts of people including a judge and law enforcement officers.

An activist investor known as a major Republican political supporter wants to wrest control of Twitter from co-founder and CEO Jack Dorsey, US media reported Friday.

Elliott Management, founded by billionaire Paul Singer, has acquired a stake in the social media firm and wants to remove Dorsey, CNBC said, citing an unnamed source.

The firm pushed for the change stating that Dorsey's attention is divided between running Twitter and his financial transactions startup Square, and that Dorsey intends to live part of each year in Africa.