Novorossiysk Commercial Sea Port (NCSP) has added a 30.3% stake in Novorossiysk Shiprepair Yard.
The Prime news agency said the slice has cost the port RUB 1.1bn ($16.81m).
The holding was sold by Russian state shipyard holding company United Shipbuilding Corporation (USC).
NCSP already owned 65.18% in the repairer, the report said.
The company said in April it planned to invest $200m in the plant to upgrade it.
