(Reuters) -AT&T ( T ) is in talks to acquire Lumen Technologies' ( LUMN ) consumer fiber operations, in a deal that could value the unit at more than $5.5 billion, Bloomberg News reported on Tuesday, citing people with knowledge of the matter.

Shares of Lumen were down more than 12% after the report.

The terms, which are not yet finalized, could change or the talks might still collapse, according to the report.

Lumen declined to comment, while AT&T ( T ) did not immediately respond to Reuters' request for comment.