Google became a wholly owned subsidiary of Alphabet in 2015.
The legal reorganization took effect on October 2, 2015. Alphabet Inc. became a new holding company, while Google continued operating its core internet businesses as Alphabet's largest subsidiary. Alphabet owned all outstanding Google stock, making Google a direct, wholly owned subsidiary rather than the parent company of the entire corporate group.
The restructuring was announced by Google in August 2015. Its purpose was to separate Google's established businesses—such as Search, YouTube, Android, and advertising—from newer or more independent ventures, including life sciences and research projects. The new structure gave those businesses greater organizational autonomy while keeping them under one parent company.
The change also brought a leadership transition. Larry Page became Alphabet's chief executive, Sergey Brin became its president, and Sundar Pichai became Google's CEO. A common mix-up is treating the announcement date as the completion date: Alphabet was announced in August, but the legal reorganization and subsidiary relationship began in October.