General Electric Co. (GE) said Thursday it agreed to sell a majority stake in its advanced materials unit to private investment group Apollo Management LP in a deal it valued at $3.8 billion.

GE, the industrial, financial services and media conglomerate based in Fairfield, said after the sale it will retain a 10 percent stake in the unit, which has annual revenue of $2.5 billion and makes silicones and quartz products used in industrial applications. The company will also hold $400 million of notes.

GE plans to use the proceeds, estimated at about $2 billion, to restructure its industrial business. The deal "is another big step in repositioning the industrial segment for faster growth and higher returns," the company said.

GE expects the sale to be final before the end of the year, pending customary closing conditions.