A "massive conglomerate" refers to a very large corporation that owns many different businesses or companies operating in various industries. Full definition
All of the companies you mentioned are owned by massive conglomerate corporations. (homevet.com)
Massive conglomerates such as General Electric are essentially holding companies for a diverse range of businesses based solely on their financial performance. (inc.com)
For income investors, there are massive conglomerates operating around the world such as ExxonMobil and BHP Billiton (NYSE: BHP), the world's biggest natural resources company. (thecollegeinvestor.com)