The shares in Adam Opel GmbH were returned to GM, the German economics ministry said in a statement on Monday.
GM lost majority ownership in Opel in June, when Germany agreed to provide a six-month emergency loan to the Ruesselsheim-based manufacturer of the Insignia hours before GM filed for a pre-packaged bankruptcy.
The trust's main job was to monitor Opel's liquidity needs and oversee the sale of a majority stake to a new investor. GM decided early in November to scrap plans to sell Opel.
(Reporting by Gernot Heller, writing by Christiaan Hetzner; Editing by Toni Reinhold)