In this paper, we find the instability ranges of a spherical symmetric structure of a collapsing object in f (T ,Θ) theory of gravity. Here, T represents the torsion scalar whileΘ is the trace of energy–momentum tensor. For this purpose, we use perturbation method up to first order in the modified field equations as well as in the dynamical equations to construct a collapse equation. The collapse equation with adiabatic index Γ is used to explore the instability ranges in Newtonian and post-Newtonian approximations. It turns out that the instability ranges depend on the dynamical variables of collapsing object.
