According to our current understanding of physics, the concept of mass as we know it does not apply to the singularity that is hypothesized to have existed at the moment of the Big Bang. The singularity is a point of infinite density and extreme curvature of spacetime, where our current laws of physics break down.
In general relativity, which is the theory that describes gravity on large scales, mass and energy are two forms of the same thing, known as the mass-energy equivalence. However, at the singularity, the energy density is so high that our current understanding of physics cannot accurately describe it.
Therefore, attempting to assign a positive, zero, or negative mass to the singularity is not meaningful within the framework of our current knowledge. The singularity represents a state where our understanding of the universe's physical properties reaches its limit, and we would require a more complete theory, such as a theory of quantum gravity, to provide a more accurate description of the early moments of the universe.