Additive actions on hyperquadrics of corank two

<abstract><p>For a projective variety $ X in {\mathbb{P}}^{m} of dimension n $, an additive action on is effective {\mathbb{G}}_{a}^{n} such that $-invariant and the induced has open orbit. Arzhantsev Popovskiy have classified actions hyperquadrics corank 0 or 1. In this paper, we give classification 2 whose singularities are not fixed by $-action.</p></abstract>