Title: Stability of Superconducting Strings  Abstract: The cosmic string can be superconducting, with fermionic or bosonic charged carriers propagating along the string. Fermionic superconducting strings emerge by introducing fermions that couple to the complex scalar field that constitutes the string. The fermion zero modes are bounded to the string as required by the index theorem. The Fermi pressure provided by fermion zero modes counterbalances the string weight, giving a stable string loop configuration, known as a vorton. The stability of vorton remains an open question. For example, the loop shrinkage may overshoot zero modes, the maximal Fermi energy of zero modes may not be large enough to avoid zero modes energetically jumping off of the string, the calculations of zero-mode decay rate are not consistent in the literature, and so on. In this talk, I will address these stability problems. Since the vorton stability depends on string dynamics (including string loop contraction and radiation), zero-mode decay, quantum tunneling, and scattering processes, I will tackle these problems at both classical and quantum levels. Our results show that the vorton can be cosmologically stable and thus it is intriguing to consider vorton dark matter.