The majority of the fibers of the gluteus maximus insert onto the

The answer is  Iliotibial tract

Explanation:

Also known as Maissiat's band and in latin as Tractus iliotibialis is responsible for the rotating, extending and abducting of the hip and greatly assist in stabilizing the side of the knees while the body is moving.

It begins at the anterolateral part of the iliac tubercle and ends at the lateral condyle near the tibia.