Federal authorities in Seattle are investigating Huawei Technologies Co. for allegedly stealing trade secrets from U.S. companies such as T-Mobile US Inc., according to a person familiar with the matter.

The investigation is tied to civil suits filed against the Chinese telecommunications giant, including a case in which a federal jury in Seattle in 2017 found Hauwei liable for the theft of T-Mobile’s robotic technology, said the person, who asked not to be named because the matter isn’t public.

The investigation is at an advanced stage, and an indictment could come soon, according to the person familiar with the matter....