  Noncommutative multi-solitons are investigated in Euclidean two-dimensional
U(n) and Grassmannian sigma models, using the auxiliary Fock-space formalism.
Their construction and moduli spaces are reviewed in some detail, unifying
abelian and nonabelian configurations. The analysis of linear perturbations
around these backgrounds reveals an unstable mode for the U(n) models but shows
stability for the Grassmannian case. For multi-solitons which are diagonal in
the Fock-space basis we explicitly evaluate the spectrum of the Hessian and
identify all zero modes. It is very suggestive but remains to be proven that
our results qualitatively extend to the entire multi-soliton moduli space.
