0_5722 The origin of phase-transition from a high temperature orthorhombic phase to a low temperature monoclinic phase in Ta₂NiSe₅ is debatable. There are two competing scenarios, namely, a structural instability with a B_2g zone center optical phonon and electronic order parameter of excitonic nature breaking the discrete set of lattice symmetries due to a sponteneous interband hybridization between Ta and Ni mediated by Coulomb many-body interactions [1-4]. We further explore the ground state symmetries and nature of collective excitations in the excitonic ordered phase of this compound.We perform a realistic modeling using Density Functional Theory as a starting point to construct a tight-binding Hamiltonian and describe the electronic correlations on a Hartree Fock level. The collective modes or excitonic susceptibilities in the ordered phase are computed within the linear response regime [5]. We see the breaking of discreet lattice symmetries due to the Ta-Ni hybridization makes the phase mode massive. The frequency of this phase mode scales with the strength of Ta-Ni hybridization. An amplitude mode appears at the gap edge and the intensity of it is less than the phase mode. The frequency of modes also show a systematic dependance with temperature. We further discuss the need for inclusion of the electron phonon coupling to provide a complete picture of this phase transition. [1] A. Subedi, Phys. Rev. Mater. 4, 083601 (2020).[2] G. Mazza, M. Rösner, L. Windgätter, S. Latini, H. Hübener, A.J. Millis, A. Rubio, and A. Georges, Phys.Rev. Lett. 124, 197601 (2020).[3] L. Windgätter, M. Rösner, G. Mazza, H. Hübener, A. Georges, A. J. Millis, S. Latini, and A. Rubio,Angel,npj Comp. Mat 7, 1–14 (2021).[4] K. Katsumi et. al, arxiV: 2211.08537 (2022).[5] Y. Murakami, D. Golež, T. Kaneko, A. Koga, A.J. Millis, and P. Werner, Phys.Rev. B. 101, 195118 (2020).